1
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Ando S, Tanaka K, Matsumoto M, Oyama Y, Tomabechi Y, Yamagata A, Shirouzu M, Nakagawa R, Okimoto N, Taiji M, Sato K, Ohama T. The luciferase-based in vivo protein-protein interaction assay revealed that CHK1 promotes PP2A and PME-1 interaction. J Biol Chem 2024; 300:107277. [PMID: 38588804 PMCID: PMC11098961 DOI: 10.1016/j.jbc.2024.107277] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2023] [Revised: 03/12/2024] [Accepted: 04/02/2024] [Indexed: 04/10/2024] Open
Abstract
Protein phosphatase 2A (PP2A) is an essential serine/threonine protein phosphatase, and its dysfunction is involved in the onset of cancer and neurodegenerative disorders. PP2A functions as a trimeric holoenzyme whose composition is regulated by the methyl-esterification (methylation) of the PP2A catalytic subunit (PP2Ac). Protein phosphatase methylesterase-1 (PME-1) is the sole PP2Ac methylesterase, and the higher PME-1 expression is observed in various cancer and neurodegenerative diseases. Apart from serving as a methylesterase, PME-1 acts as a PP2A inhibitory protein, binding directly to PP2Ac and suppressing its activity. The intricate function of PME-1 hinders drug development by targeting the PME-1/PP2Ac axis. This study applied the NanoBiT system, a bioluminescence-based protein interaction assay, to elucidate the molecular mechanism that modulates unknown PME-1/PP2Ac protein-protein interaction (PPI). Compound screening identified that the CHK1 inhibitors inhibited PME-1/PP2Ac association without affecting PP2Ac methylation levels. CHK1 directly phosphorylates PP2Ac to promote PME-1 association. Phospho-mass spectrometry identified multiple phospho-sites on PP2Ac, including the Thr219, that affect PME-1 interaction. An anti-phospho-Thr219 PP2Ac antibody was generated and showed that CHK1 regulates the phosphorylation levels of this site in cells. On the contrary, in vitro phosphatase assay showed that CHK1 is the substrate of PP2A, and PME-1 hindered PP2A-mediated dephosphorylation of CHK1. Our data provides novel insights into the molecular mechanisms governing the PME-1/PP2Ac PPI and the triad relationship between PP2A, PME-1, and CHK1.
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Affiliation(s)
- Sana Ando
- Laboratory of Veterinary Pharmacology, Joint Faculty of Veterinary Medicine, Yamaguchi University, Yamaguchi, Japan
| | - Keiko Tanaka
- Laboratory of Veterinary Pharmacology, Joint Faculty of Veterinary Medicine, Yamaguchi University, Yamaguchi, Japan
| | - Maharu Matsumoto
- Laboratory of Veterinary Pharmacology, Joint Faculty of Veterinary Medicine, Yamaguchi University, Yamaguchi, Japan
| | - Yuki Oyama
- Laboratory of Veterinary Pharmacology, Joint Faculty of Veterinary Medicine, Yamaguchi University, Yamaguchi, Japan
| | - Yuri Tomabechi
- Laboratory for Protein Functional and Structural Biology, RIKEN Center for Biosystems Dynamics Research, Yokohama, Kanagawa, Japan
| | - Atsushi Yamagata
- Laboratory for Protein Functional and Structural Biology, RIKEN Center for Biosystems Dynamics Research, Yokohama, Kanagawa, Japan
| | - Mikako Shirouzu
- Laboratory for Protein Functional and Structural Biology, RIKEN Center for Biosystems Dynamics Research, Yokohama, Kanagawa, Japan
| | - Reiko Nakagawa
- Laboratory for Cell-Free Protein Synthesis, RIKEN Center for Biosystems Dynamics Research, Kobe, Hyogo, Japan
| | - Noriaki Okimoto
- Laboratory for Computational Molecular Design, RIKEN Center for Biosystems Dynamics Research (BDR), Osaka, Japan; Drug Discovery Molecular Simulation Platform Unit, RIKEN Center for Biosystems Dynamics Research (BDR), Osaka, Japan
| | - Makoto Taiji
- Laboratory for Computational Molecular Design, RIKEN Center for Biosystems Dynamics Research (BDR), Osaka, Japan; Drug Discovery Molecular Simulation Platform Unit, RIKEN Center for Biosystems Dynamics Research (BDR), Osaka, Japan
| | - Koichi Sato
- Laboratory of Veterinary Pharmacology, Joint Faculty of Veterinary Medicine, Yamaguchi University, Yamaguchi, Japan; Research Institute for Cell Design Medical Science, Yamaguchi University, Yamaguchi, Japan
| | - Takashi Ohama
- Laboratory of Veterinary Pharmacology, Joint Faculty of Veterinary Medicine, Yamaguchi University, Yamaguchi, Japan; Research Institute for Cell Design Medical Science, Yamaguchi University, Yamaguchi, Japan.
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2
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Lara MK, Brabec JL, Hernan AE, Scott RC, Tyler AL, Mahoney JM. Network-based analysis predicts interacting genetic modifiers from a meta-mapping study of spike-wave discharge in mice. GENES, BRAIN, AND BEHAVIOR 2024; 23:e12879. [PMID: 38444174 PMCID: PMC10915378 DOI: 10.1111/gbb.12879] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/22/2023] [Revised: 11/29/2023] [Accepted: 12/19/2023] [Indexed: 03/07/2024]
Abstract
Absence seizures are characterized by brief lapses in awareness accompanied by a hallmark spike-and-wave discharge (SWD) electroencephalographic pattern and are common to genetic generalized epilepsies (GGEs). While numerous genes have been associated with increased risk, including some Mendelian forms with a single causal allele, most cases of GGE are idiopathic and there are many unknown genetic modifiers of GGE influencing risk and severity. In a previous meta-mapping study, crosses between transgenic C57BL/6 and C3HeB/FeJ strains, each carrying one of three SWD-causing mutations (Gabrg2tm1Spet(R43Q) , Scn8a8j or Gria4spkw1 ), demonstrated an antagonistic epistatic interaction between loci on mouse chromosomes 2 and 7 influencing SWD. These results implicate universal modifiers in the B6 background that mitigate SWD severity through a common pathway, independent of the causal mutation. In this study, we prioritized candidate modifiers in these interacting loci. Our approach integrated human genome-wide association results with gene interaction networks and mouse brain gene expression to prioritize candidate genes and pathways driving variation in SWD outcomes. We considered candidate genes that are functionally associated with human GGE risk genes and genes with evidence for coding or non-coding allele effects between the B6 and C3H backgrounds. Our analyses output a summary ranking of gene pairs, one gene from each locus, as candidates for explaining the epistatic interaction. Our top-ranking gene pairs implicate microtubule function, cytoskeletal stability and cell cycle regulation as novel hypotheses about the source of SWD variation across strain backgrounds, which could clarify underlying mechanisms driving differences in GGE severity in humans.
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Affiliation(s)
- Montana Kay Lara
- Department of Neurological SciencesUniversity of VermontBurlingtonVermontUSA
| | - Jeffrey L. Brabec
- Department of Neurological SciencesUniversity of VermontBurlingtonVermontUSA
| | - Amanda E. Hernan
- Department of Neurological SciencesUniversity of VermontBurlingtonVermontUSA
- Division of NeuroscienceNemours Children's HealthWilmingtonDelawareUSA
- Department of Psychological and Brain SciencesUniversity of DelawareNewarkDelawareUSA
| | - Rod C. Scott
- Division of NeuroscienceNemours Children's HealthWilmingtonDelawareUSA
- Department of Psychological and Brain SciencesUniversity of DelawareNewarkDelawareUSA
| | | | - J. Matthew Mahoney
- Department of Neurological SciencesUniversity of VermontBurlingtonVermontUSA
- The Jackson LaboratoryBar HarborMaineUSA
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3
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Ikeda S, Sato K, Ohama T. Transcriptome analysis revealed that PME-1 suppresses inflammatory signaling, activates PI3K/Akt signaling, and promotes epithelial-mesenchymal transition. Biochem Biophys Res Commun 2024; 692:149148. [PMID: 38043157 DOI: 10.1016/j.bbrc.2023.149148] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2023] [Revised: 09/28/2023] [Accepted: 10/23/2023] [Indexed: 12/05/2023]
Abstract
Protein phosphatase 2A (PP2A) is an essential serine/threonine protein phosphatase that belongs to the type2A protein phosphatase family with PP4 and PP6. PP2A functions as a trimeric holoenzyme, and the composition of the trimer is regulated by the methyl-esterification (methylation) of PP2A. Demethylation of PP2A is catalyzed by protein phosphatase methyl-esterase-1 (PME-1). Despite the physiological and pathophysiological importance of PME-1, the impact of changes in PME-1 expression on the transcriptome has not been reported. This study provides transcriptome data to gain a comprehensive understanding of the effects of PME-1 knockout on intracellular signaling of mouse embryonic fibroblasts. Our data showed that PME-1 suppresses inflammatory signaling, activates PI3K/Akt signaling, and promotes epithelial-mesenchymal transition.
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Affiliation(s)
- Shunta Ikeda
- Laboratory of Veterinary Pharmacology, Joint Faculty of Veterinary Medicine, Yamaguchi University, 1677-1 Yoshida, Yamaguchi 753-8515, Japan
| | - Koichi Sato
- Laboratory of Veterinary Pharmacology, Joint Faculty of Veterinary Medicine, Yamaguchi University, 1677-1 Yoshida, Yamaguchi 753-8515, Japan
| | - Takashi Ohama
- Laboratory of Veterinary Pharmacology, Joint Faculty of Veterinary Medicine, Yamaguchi University, 1677-1 Yoshida, Yamaguchi 753-8515, Japan.
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4
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Fujiwara R, Zhai SN, Liang D, Shah AP, Tracey M, Ma XK, Fields CJ, Mendoza-Figueroa MS, Meline MC, Tatomer DC, Yang L, Wilusz JE. IntS6 and the Integrator phosphatase module tune the efficiency of select premature transcription termination events. Mol Cell 2023; 83:4445-4460.e7. [PMID: 37995689 PMCID: PMC10841813 DOI: 10.1016/j.molcel.2023.10.035] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2023] [Revised: 10/12/2023] [Accepted: 10/25/2023] [Indexed: 11/25/2023]
Abstract
The metazoan-specific Integrator complex catalyzes 3' end processing of small nuclear RNAs (snRNAs) and premature termination that attenuates the transcription of many protein-coding genes. Integrator has RNA endonuclease and protein phosphatase activities, but it remains unclear if both are required for complex function. Here, we show IntS6 (Integrator subunit 6) over-expression blocks Integrator function at a subset of Drosophila protein-coding genes, although having no effect on snRNAs or attenuation of other loci. Over-expressed IntS6 titrates protein phosphatase 2A (PP2A) subunits, thereby only affecting gene loci where phosphatase activity is necessary for Integrator function. IntS6 functions analogous to a PP2A regulatory B subunit as over-expression of canonical B subunits, which do not bind Integrator, is also sufficient to inhibit Integrator activity. These results show that the phosphatase module is critical at only a subset of Integrator-regulated genes and point to PP2A recruitment as a tunable step that modulates transcription termination efficiency.
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Affiliation(s)
- Rina Fujiwara
- Verna and Marrs McLean Department of Biochemistry and Molecular Pharmacology, Therapeutic Innovation Center, Baylor College of Medicine, Houston, TX 77030, USA
| | - Si-Nan Zhai
- Shanghai Institute of Nutrition and Health, University of Chinese Academy of Sciences, Chinese Academy of Sciences, Shanghai 200031, China; Center for Molecular Medicine, Children's Hospital, Fudan University and Shanghai Key Laboratory of Medical Epigenetics, International Laboratory of Medical Epigenetics and Metabolism, Ministry of Science and Technology, Institutes of Biomedical Sciences, Fudan University, Shanghai 200032, China
| | - Dongming Liang
- Department of Biochemistry and Biophysics, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA 19104, USA
| | - Aayushi P Shah
- Verna and Marrs McLean Department of Biochemistry and Molecular Pharmacology, Therapeutic Innovation Center, Baylor College of Medicine, Houston, TX 77030, USA
| | - Matthew Tracey
- Department of Biochemistry and Biophysics, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA 19104, USA
| | - Xu-Kai Ma
- Center for Molecular Medicine, Children's Hospital, Fudan University and Shanghai Key Laboratory of Medical Epigenetics, International Laboratory of Medical Epigenetics and Metabolism, Ministry of Science and Technology, Institutes of Biomedical Sciences, Fudan University, Shanghai 200032, China
| | - Christopher J Fields
- Verna and Marrs McLean Department of Biochemistry and Molecular Pharmacology, Therapeutic Innovation Center, Baylor College of Medicine, Houston, TX 77030, USA
| | - María Saraí Mendoza-Figueroa
- Department of Biochemistry and Biophysics, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA 19104, USA
| | - Michele C Meline
- Department of Biochemistry and Biophysics, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA 19104, USA
| | - Deirdre C Tatomer
- Department of Biochemistry and Biophysics, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA 19104, USA
| | - Li Yang
- Center for Molecular Medicine, Children's Hospital, Fudan University and Shanghai Key Laboratory of Medical Epigenetics, International Laboratory of Medical Epigenetics and Metabolism, Ministry of Science and Technology, Institutes of Biomedical Sciences, Fudan University, Shanghai 200032, China
| | - Jeremy E Wilusz
- Verna and Marrs McLean Department of Biochemistry and Molecular Pharmacology, Therapeutic Innovation Center, Baylor College of Medicine, Houston, TX 77030, USA.
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5
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Rasool RU, O'Connor CM, Das CK, Alhusayan M, Verma BK, Islam S, Frohner IE, Deng Q, Mitchell-Velasquez E, Sangodkar J, Ahmed A, Linauer S, Mudrak I, Rainey J, Zawacki KP, Suhan TK, Callahan CG, Rebernick R, Natesan R, Siddiqui J, Sauter G, Thomas D, Wang S, Taylor DJ, Simon R, Cieslik M, Chinnaiyan AM, Busino L, Ogris E, Narla G, Asangani IA. Loss of LCMT1 and biased protein phosphatase 2A heterotrimerization drive prostate cancer progression and therapy resistance. Nat Commun 2023; 14:5253. [PMID: 37644036 PMCID: PMC10465527 DOI: 10.1038/s41467-023-40760-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2023] [Accepted: 08/09/2023] [Indexed: 08/31/2023] Open
Abstract
Loss of the tumor suppressive activity of the protein phosphatase 2A (PP2A) is associated with cancer, but the underlying molecular mechanisms are unclear. PP2A holoenzyme comprises a heterodimeric core, a scaffolding A subunit and a catalytic C subunit, and one of over 20 distinct substrate-directing regulatory B subunits. Methylation of the C subunit regulates PP2A heterotrimerization, affecting B subunit binding and substrate specificity. Here, we report that the leucine carboxy methyltransferase (LCMT1), which methylates the L309 residue of the C subunit, acts as a suppressor of androgen receptor (AR) addicted prostate cancer (PCa). Decreased methyl-PP2A-C levels in prostate tumors is associated with biochemical recurrence and metastasis. Silencing LCMT1 increases AR activity and promotes castration-resistant prostate cancer growth. LCMT1-dependent methyl-sensitive AB56αCme heterotrimers target AR and its critical coactivator MED1 for dephosphorylation, resulting in the eviction of the AR-MED1 complex from chromatin and loss of target gene expression. Mechanistically, LCMT1 is regulated by S6K1-mediated phosphorylation-induced degradation requiring the β-TRCP, leading to acquired resistance to anti-androgens. Finally, feedforward stabilization of LCMT1 by small molecule activator of phosphatase (SMAP) results in attenuation of AR-signaling and tumor growth inhibition in anti-androgen refractory PCa. These findings highlight methyl-PP2A-C as a prognostic marker and that the loss of LCMT1 is a major determinant in AR-addicted PCa, suggesting therapeutic potential for AR degraders or PP2A modulators in prostate cancer treatment.
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Affiliation(s)
- Reyaz Ur Rasool
- Department of Cancer Biology, Perelman School of Medicine, University of Pennsylvania, 421 Curie Boulevard, BRBII/III, Philadelphia, PA, 19104, USA
| | - Caitlin M O'Connor
- Division of Genetic Medicine, Department of Internal Medicine, University of Michigan, Ann Arbor, MI, 48105, USA
- Rogel Cancer Center, University of Michigan, Ann Arbor, MI, 48109, USA
| | - Chandan Kanta Das
- Department of Cancer Biology, Perelman School of Medicine, University of Pennsylvania, 421 Curie Boulevard, BRBII/III, Philadelphia, PA, 19104, USA
| | - Mohammed Alhusayan
- Department of Cancer Biology, Perelman School of Medicine, University of Pennsylvania, 421 Curie Boulevard, BRBII/III, Philadelphia, PA, 19104, USA
| | - Brijesh Kumar Verma
- Department of Cancer Biology, Perelman School of Medicine, University of Pennsylvania, 421 Curie Boulevard, BRBII/III, Philadelphia, PA, 19104, USA
| | - Sehbanul Islam
- Department of Cancer Biology, Perelman School of Medicine, University of Pennsylvania, 421 Curie Boulevard, BRBII/III, Philadelphia, PA, 19104, USA
| | - Ingrid E Frohner
- Center for Medical Biochemistry, Max Perutz Labs, Medical University of Vienna, Dr. Bohr-Gasse 9/2, Vienna, 1030, Austria
| | - Qu Deng
- Department of Cancer Biology, Perelman School of Medicine, University of Pennsylvania, 421 Curie Boulevard, BRBII/III, Philadelphia, PA, 19104, USA
| | - Erick Mitchell-Velasquez
- Department of Cancer Biology, Perelman School of Medicine, University of Pennsylvania, 421 Curie Boulevard, BRBII/III, Philadelphia, PA, 19104, USA
| | - Jaya Sangodkar
- Division of Genetic Medicine, Department of Internal Medicine, University of Michigan, Ann Arbor, MI, 48105, USA
- Rogel Cancer Center, University of Michigan, Ann Arbor, MI, 48109, USA
| | - Aqila Ahmed
- Division of Genetic Medicine, Department of Internal Medicine, University of Michigan, Ann Arbor, MI, 48105, USA
- Rogel Cancer Center, University of Michigan, Ann Arbor, MI, 48109, USA
| | - Sarah Linauer
- Center for Medical Biochemistry, Max Perutz Labs, Medical University of Vienna, Dr. Bohr-Gasse 9/2, Vienna, 1030, Austria
| | - Ingrid Mudrak
- Center for Medical Biochemistry, Max Perutz Labs, Medical University of Vienna, Dr. Bohr-Gasse 9/2, Vienna, 1030, Austria
| | - Jessica Rainey
- Department of Cancer Biology, Perelman School of Medicine, University of Pennsylvania, 421 Curie Boulevard, BRBII/III, Philadelphia, PA, 19104, USA
| | - Kaitlin P Zawacki
- Division of Genetic Medicine, Department of Internal Medicine, University of Michigan, Ann Arbor, MI, 48105, USA
- Rogel Cancer Center, University of Michigan, Ann Arbor, MI, 48109, USA
| | - Tahra K Suhan
- Division of Genetic Medicine, Department of Internal Medicine, University of Michigan, Ann Arbor, MI, 48105, USA
- Rogel Cancer Center, University of Michigan, Ann Arbor, MI, 48109, USA
| | - Catherine G Callahan
- Division of Genetic Medicine, Department of Internal Medicine, University of Michigan, Ann Arbor, MI, 48105, USA
- Rogel Cancer Center, University of Michigan, Ann Arbor, MI, 48109, USA
| | - Ryan Rebernick
- Department of Pathology and Rogel Cancer Center, University of Michigan Medical School, Ann Arbor, MI, USA
- Michigan Center for Translational Pathology, University of Michigan, Ann Arbor, MI, USA
| | - Ramakrishnan Natesan
- Department of Cancer Biology, Perelman School of Medicine, University of Pennsylvania, 421 Curie Boulevard, BRBII/III, Philadelphia, PA, 19104, USA
| | - Javed Siddiqui
- Department of Pathology and Rogel Cancer Center, University of Michigan Medical School, Ann Arbor, MI, USA
- Michigan Center for Translational Pathology, University of Michigan, Ann Arbor, MI, USA
| | - Guido Sauter
- Institute of Pathology, University Medical Center Hamburg-Eppendorf, 20246, Hamburg, Germany
| | - Dafydd Thomas
- Michigan Center for Translational Pathology, University of Michigan, Ann Arbor, MI, USA
| | - Shaomeng Wang
- Departments of Internal Medicine, Pharmacology, and Medicinal Chemistry, University of Michigan, Ann Arbor, MI, USA
| | - Derek J Taylor
- Department of Biochemistry Case Western Reserve University School of Medicine, Cleveland, OH, 44106, USA
| | - Ronald Simon
- Institute of Pathology, University Medical Center Hamburg-Eppendorf, 20246, Hamburg, Germany
| | - Marcin Cieslik
- Department of Pathology and Rogel Cancer Center, University of Michigan Medical School, Ann Arbor, MI, USA
- Michigan Center for Translational Pathology, University of Michigan, Ann Arbor, MI, USA
| | - Arul M Chinnaiyan
- Department of Pathology and Rogel Cancer Center, University of Michigan Medical School, Ann Arbor, MI, USA
- Michigan Center for Translational Pathology, University of Michigan, Ann Arbor, MI, USA
| | - Luca Busino
- Department of Cancer Biology, Perelman School of Medicine, University of Pennsylvania, 421 Curie Boulevard, BRBII/III, Philadelphia, PA, 19104, USA
| | - Egon Ogris
- Center for Medical Biochemistry, Max Perutz Labs, Medical University of Vienna, Dr. Bohr-Gasse 9/2, Vienna, 1030, Austria.
| | - Goutham Narla
- Division of Genetic Medicine, Department of Internal Medicine, University of Michigan, Ann Arbor, MI, 48105, USA.
- Rogel Cancer Center, University of Michigan, Ann Arbor, MI, 48109, USA.
| | - Irfan A Asangani
- Department of Cancer Biology, Perelman School of Medicine, University of Pennsylvania, 421 Curie Boulevard, BRBII/III, Philadelphia, PA, 19104, USA.
- Abramson Family Cancer Research Institute, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA.
- Epigenetics Institute, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA.
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6
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Guffens L, Derua R, Janssens V. PME-1 sensitizes glioblastoma cells to oxidative stress-induced cell death by attenuating PP2A-B55α-mediated inactivation of MAPKAPK2-RIPK1 signaling. Cell Death Discov 2023; 9:265. [PMID: 37500619 PMCID: PMC10374899 DOI: 10.1038/s41420-023-01572-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2023] [Revised: 07/13/2023] [Accepted: 07/20/2023] [Indexed: 07/29/2023] Open
Abstract
Glioblastoma (GBM) is the most common primary brain tumor in adults. Current standard therapy is surgery followed by radiotherapy, with concurrent and adjuvant temozolomide chemotherapy. GBM is characterized by almost uniformly fatal outcomes, highlighting the unmet clinical need for more efficient, biomarker-guided treatments. Protein phosphatase methylesterase-1 (PME-1), a regulator of the tumor suppressive phosphatase PP2A, promotes PP2A demethylation and inactivation, and is overexpressed in 44% of GBM, associated with increased tumor grade and cellular proliferation. Here, we aimed to investigate how reactive oxygen species (ROS), a frequent by-product of radiotherapy and temozolomide chemotherapy, regulate PP2A function via its methylesterase PME-1, and how PME-1 overexpression impacts the response of GBM cells to oxidative stress. We found that in two glioblastoma cell lines, U87MG and U251MG, expression of PME-1 is positively correlated with the sensitivity of the cells to H2O2 or t-BHP-induced oxidative stress. Experiments using the irreversible pharmacologic PME-1 inhibitor, AMZ30, and different PME-1 mutants, revealed that the methylesterase function, the PP2A binding capacity, and the nuclear localization of PME-1 are all important for the sensitizing effect of PME-1 expression. Furthermore, we identified increased nuclear localization of the PP2A-B55α subunit, increased binding of PP2A-B55α to PME-1, and increased B55α-bound PP2A-C demethylation upon oxidative stress. Lastly, we uncovered increased stress-induced phosphorylation and activity of MAPKAPK2 and RIPK1 in PME-1 overexpressing U87MG cells, which caused the observed sensitization to t-BHP treatment. Our data reveal a novel role for PME-1 in oxidative stress-induced GBM cell death, regulating nuclear PP2A-B55α activity and MAPKAPK2-RIPK1 signaling. Patients with GBM tumors overexpressing PME-1, although having a worse prognosis due to increased cellular proliferation of the tumor, could actually be more responsive to oxidative stress-inducing therapies.
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Affiliation(s)
- Liesbeth Guffens
- Laboratory of Protein Phosphorylation & Proteomics, Dept. Cellular & Molecular Medicine, KU Leuven, B-3000, Leuven, Belgium
- KU Leuven Cancer Institute (LKI), B-3000, Leuven, Belgium
| | - Rita Derua
- Laboratory of Protein Phosphorylation & Proteomics, Dept. Cellular & Molecular Medicine, KU Leuven, B-3000, Leuven, Belgium
- SyBioMa, KU Leuven, B-3000, Leuven, Belgium
| | - Veerle Janssens
- Laboratory of Protein Phosphorylation & Proteomics, Dept. Cellular & Molecular Medicine, KU Leuven, B-3000, Leuven, Belgium.
- KU Leuven Cancer Institute (LKI), B-3000, Leuven, Belgium.
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7
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Simpson LM, Fulcher LJ, Sathe G, Brewer A, Zhao JF, Squair DR, Crooks J, Wightman M, Wood NT, Gourlay R, Varghese J, Soares RF, Sapkota GP. An affinity-directed phosphatase, AdPhosphatase, system for targeted protein dephosphorylation. Cell Chem Biol 2023; 30:188-202.e6. [PMID: 36720221 DOI: 10.1016/j.chembiol.2023.01.003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2022] [Revised: 11/07/2022] [Accepted: 01/10/2023] [Indexed: 02/02/2023]
Abstract
Reversible protein phosphorylation, catalyzed by protein kinases and phosphatases, is a fundamental process that controls protein function and intracellular signaling. Failure of phospho-control accounts for many human diseases. While a kinase phosphorylates multiple substrates, a substrate is often phosphorylated by multiple kinases. This renders phospho-control at the substrate level challenging, as it requires inhibition of multiple kinases, which would thus affect other kinase substrates. Here, we describe the development and application of the affinity-directed phosphatase (AdPhosphatase) system for targeted dephosphorylation of specific phospho-substrates. By deploying the Protein Phosphatase 1 or 2A catalytic subunits conjugated to an antigen-stabilized anti-GFP nanobody, we can promote the dephosphorylation of two independent phospho-proteins, FAM83D or ULK1, knocked in with GFP-tags using CRISPR-Cas9, with exquisite specificity. By redirecting protein phosphatases to neo-substrates through nanobody-mediated proximity, AdPhosphatase can alter the phospho-status and function of target proteins and thus, offers a new modality for potential drug discovery approaches.
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Affiliation(s)
- Luke M Simpson
- Medical Research Council (MRC) Protein Phosphorylation and Ubiquitylation Unit, School of Life Sciences, University of Dundee, Dundee DD1 5EH, UK
| | - Luke J Fulcher
- Medical Research Council (MRC) Protein Phosphorylation and Ubiquitylation Unit, School of Life Sciences, University of Dundee, Dundee DD1 5EH, UK
| | - Gajanan Sathe
- Medical Research Council (MRC) Protein Phosphorylation and Ubiquitylation Unit, School of Life Sciences, University of Dundee, Dundee DD1 5EH, UK
| | - Abigail Brewer
- Medical Research Council (MRC) Protein Phosphorylation and Ubiquitylation Unit, School of Life Sciences, University of Dundee, Dundee DD1 5EH, UK
| | - Jin-Feng Zhao
- Medical Research Council (MRC) Protein Phosphorylation and Ubiquitylation Unit, School of Life Sciences, University of Dundee, Dundee DD1 5EH, UK
| | - Daniel R Squair
- Medical Research Council (MRC) Protein Phosphorylation and Ubiquitylation Unit, School of Life Sciences, University of Dundee, Dundee DD1 5EH, UK
| | - Jennifer Crooks
- Medical Research Council (MRC) Protein Phosphorylation and Ubiquitylation Unit, School of Life Sciences, University of Dundee, Dundee DD1 5EH, UK
| | - Melanie Wightman
- Medical Research Council (MRC) Protein Phosphorylation and Ubiquitylation Unit, School of Life Sciences, University of Dundee, Dundee DD1 5EH, UK
| | - Nicola T Wood
- Medical Research Council (MRC) Protein Phosphorylation and Ubiquitylation Unit, School of Life Sciences, University of Dundee, Dundee DD1 5EH, UK
| | - Robert Gourlay
- Medical Research Council (MRC) Protein Phosphorylation and Ubiquitylation Unit, School of Life Sciences, University of Dundee, Dundee DD1 5EH, UK
| | - Joby Varghese
- Medical Research Council (MRC) Protein Phosphorylation and Ubiquitylation Unit, School of Life Sciences, University of Dundee, Dundee DD1 5EH, UK
| | - Renata F Soares
- Medical Research Council (MRC) Protein Phosphorylation and Ubiquitylation Unit, School of Life Sciences, University of Dundee, Dundee DD1 5EH, UK
| | - Gopal P Sapkota
- Medical Research Council (MRC) Protein Phosphorylation and Ubiquitylation Unit, School of Life Sciences, University of Dundee, Dundee DD1 5EH, UK.
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8
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Azumi M, Yoshie M, Takano W, Ishida A, Kusama K, Tamura K. The Impact of Eribulin on Stathmin Dynamics and Paclitaxel Sensitivity in Ovarian Cancer Cells. Biol Pharm Bull 2022; 45:1627-1635. [DOI: 10.1248/bpb.b22-00251] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Affiliation(s)
- Mana Azumi
- Department of Endocrine Pharmacology, Tokyo University of Pharmacy and Life Sciences
| | - Mikihiro Yoshie
- Department of Endocrine Pharmacology, Tokyo University of Pharmacy and Life Sciences
| | - Wataru Takano
- Department of Endocrine Pharmacology, Tokyo University of Pharmacy and Life Sciences
| | - Akari Ishida
- Department of Endocrine Pharmacology, Tokyo University of Pharmacy and Life Sciences
| | - Kazuya Kusama
- Department of Endocrine Pharmacology, Tokyo University of Pharmacy and Life Sciences
| | - Kazuhiro Tamura
- Department of Endocrine Pharmacology, Tokyo University of Pharmacy and Life Sciences
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9
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Haanen TJ, O'Connor CM, Narla G. Biased holoenzyme assembly of protein phosphatase 2A (PP2A): From cancer to small molecules. J Biol Chem 2022; 298:102656. [PMID: 36328247 PMCID: PMC9707111 DOI: 10.1016/j.jbc.2022.102656] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2022] [Revised: 10/25/2022] [Accepted: 10/27/2022] [Indexed: 11/06/2022] Open
Abstract
Protein phosphatase 2A (PP2A) is a family of serine threonine phosphatases responsible for regulating protein phosphorylation, thus opposing the activity of cellular kinases. PP2A is composed of a catalytic subunit (PP2A Cα/β) and scaffolding subunit (PP2A Aα/β) and various substrate-directing B regulatory subunits. PP2A biogenesis is regulated at multiple levels. For example, the sequestration of the free catalytic subunit during the process of biogenesis avoids promiscuous phosphatase activity. Posttranslational modifications of PP2A C direct PP2A heterotrimeric formation. Additionally, PP2A functions as a haploinsufficient tumor suppressor, where attenuated PP2A enzymatic activity creates a permissive environment for oncogenic transformation. Recent work studying PP2A in cancer showed that its role in tumorigenesis is more nuanced, with some holoenzymes being tumor suppressive, while others are required for oncogenic transformation. In cancer biology, PP2A function is modulated through various mechanisms including the displacement of specific B regulatory subunits by DNA tumor viral antigens, by recurrent mutations, and through loss of carboxymethyl-sensitive heterotrimeric complexes. In aggregate, these alterations bias PP2A activity away from its tumor suppressive functions and toward oncogenic ones. From a therapeutic perspective, molecular glues and disruptors present opportunities for both the selective stabilization of tumor-suppressive holoenzymes and disruption of holoenzymes that are pro-oncogenic. Collectively, these approaches represent an attractive cancer therapy for a wide range of tumor types. This review will discuss the mechanisms by which PP2A holoenzyme formation is dysregulated in cancer and the current therapies that are aimed at biasing heterotrimer formation of PP2A for the treatment of cancer.
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10
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Schuhmacher D, Sontag JM, Sontag E. A Novel Role of PP2A Methylation in the Regulation of Tight Junction Assembly and Integrity. Front Cell Dev Biol 2022; 10:911279. [PMID: 35912112 PMCID: PMC9326217 DOI: 10.3389/fcell.2022.911279] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2022] [Accepted: 06/21/2022] [Indexed: 12/04/2022] Open
Abstract
Tight junctions (TJs) are multiprotein complexes essential for cell polarity and the barrier function of epithelia. The major signaling molecule, protein serine/threonine phosphatase 2A (PP2A), interacts with the TJ and modulates the phosphorylation state of TJ proteins. An important PP2A regulatory mechanism involves leucine carboxyl methyltransferase-1 (LCMT1)-dependent methylation and protein phosphatase methylesterase-1 (PME1)-mediated demethylation of its catalytic subunit on Leu309. Here, using MDCK cells, we show that overexpression of LCMT1, which enhances cellular PP2A methylation, inhibits TJ formation, induces TJ ruffling, and decreases TJ barrier function. Conversely, overexpression of PME1 accelerates TJ assembly and enhances TJ barrier function. PME1-dependent PP2A demethylation increases during early Ca2+-dependent junctional assembly. Inhibition of endogenous PME1 delays the initial Ca2+-mediated redistribution of TJ proteins to cell-cell contacts and affects TJ morphology and barrier function. Manipulating one-carbon metabolism modulates TJ assembly, at least in part by affecting PP2A methylation state. The integrity of PP2A methylation is critical for proper targeting of PP2A to the TJ. It is necessary for PP2A complex formation with the TJ proteins, occludin and ZO-1, and proteins of the PAR complex, Par3 and atypical protein kinase C ζ (aPKCζ), which play a key role in development of cell polarity. Expression of a methylation incompetent PP2A mutant induces defects in TJ assembly and barrier function. aPKCζ-mediated Par3 phosphorylation is also required for targeting of the PP2A ABαC holoenzyme to the TJ. Our findings provide the first evidence for a role of LCMT1, PME1 and PP2A methylation/demethylation processes in modulating TJ assembly and functional integrity. They also position PP2A at the interface of one-carbon metabolism and the regulation of key TJ and polarity proteins that become deregulated in many human diseases.
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11
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Sontag JM, Schuhmacher D, Taleski G, Jordan A, Khan S, Hoffman A, Gomez RJ, Mazalouskas MD, Hanks SK, Spiller BW, Sontag E, Wadzinski BE. A new paradigm for regulation of protein phosphatase 2A function via Src and Fyn kinase-mediated tyrosine phosphorylation. J Biol Chem 2022; 298:102248. [PMID: 35820485 PMCID: PMC9396060 DOI: 10.1016/j.jbc.2022.102248] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2022] [Revised: 07/01/2022] [Accepted: 07/04/2022] [Indexed: 12/01/2022] Open
Abstract
Protein phosphatase 2A (PP2A) is a major phospho-Ser/Thr phosphatase and a key regulator of cellular signal transduction pathways. While PP2A dysfunction has been linked to human cancer and neurodegenerative disorders such as Alzheimer’s disease (AD), PP2A regulation remains relatively poorly understood. It has been reported that the PP2A catalytic subunit (PP2Ac) is inactivated by a single phosphorylation at the Tyr307 residue by tyrosine kinases such as v-Src. However, multiple mass spectrometry studies have revealed the existence of other putative PP2Ac phosphorylation sites in response to activation of Src and Fyn, two major Src family kinases (SFKs). Here, using PP2Ac phosphomutants and novel phosphosite-specific PP2Ac antibodies, we show that cellular pools of PP2Ac are instead phosphorylated on both Tyr127 and Tyr284 upon Src activation, and on Tyr284 following Fyn activation. We found these phosphorylation events enhanced the interaction of PP2Ac with SFKs. In addition, we reveal SFK-mediated phosphorylation of PP2Ac at Y284 promotes dissociation of the regulatory Bα subunit, altering PP2A substrate specificity; the phosphodeficient Y127/284F and Y284F PP2Ac mutants prevented SFK-mediated phosphorylation of Tau at the CP13 (pSer202) epitope, a pathological hallmark of AD, and SFK-dependent activation of ERK, a major growth regulatory kinase upregulated in many cancers. Our findings demonstrate a novel PP2A regulatory mechanism that challenges the existing dogma on the inhibition of PP2A catalytic activity by Tyr307 phosphorylation. We propose dysregulation of SFK signaling in cancer and AD can lead to alterations in PP2A phosphorylation and subsequent deregulation of key PP2A substrates, including ERK and Tau.
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Affiliation(s)
- Jean-Marie Sontag
- School of Biomedical Sciences and Pharmacy, University of Newcastle, Callaghan, NSW, Australia
| | - Diana Schuhmacher
- School of Biomedical Sciences and Pharmacy, University of Newcastle, Callaghan, NSW, Australia
| | - Goce Taleski
- School of Biomedical Sciences and Pharmacy, University of Newcastle, Callaghan, NSW, Australia
| | - Anthony Jordan
- Department of Pharmacology, Vanderbilt University School of Medicine, Nashville, TN, USA
| | - Sarah Khan
- Department of Pharmacology, Vanderbilt University School of Medicine, Nashville, TN, USA
| | - Alexander Hoffman
- School of Biomedical Sciences and Pharmacy, University of Newcastle, Callaghan, NSW, Australia
| | - Rey J Gomez
- Department of Pharmacology, Vanderbilt University School of Medicine, Nashville, TN, USA
| | - Matthew D Mazalouskas
- Department of Pharmacology, Vanderbilt University School of Medicine, Nashville, TN, USA
| | - Steven K Hanks
- Department of Cell and Developmental Biology, Vanderbilt University School of Medicine, Nashville, TN, USA
| | - Benjamin W Spiller
- Department of Pharmacology, Vanderbilt University School of Medicine, Nashville, TN, USA
| | - Estelle Sontag
- School of Biomedical Sciences and Pharmacy, University of Newcastle, Callaghan, NSW, Australia.
| | - Brian E Wadzinski
- Department of Pharmacology, Vanderbilt University School of Medicine, Nashville, TN, USA.
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12
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Qu G, Xu Z, Tuo W, Li C, Lillehoj H, Wan G, Gong H, Huang J, Tian G, Li S, Liu Y, Liu L. Immunoproteomic analysis of the sporozoite antigens of Eimeria necatrix. Vet Parasitol 2021; 301:109642. [PMID: 34971828 DOI: 10.1016/j.vetpar.2021.109642] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2021] [Revised: 12/22/2021] [Accepted: 12/23/2021] [Indexed: 11/19/2022]
Abstract
Eimeria necatrix, an apicomplexan protozoa of the genus Eimeria, causes intestinal coccidiosis that can reduce growth performance of poultry and result in high mortality in older chickens. In this report, the whole sporozoite proteins of E.necatrix were studied by two-dimensional electrophoresis (2-DE) and Western blotting using hyper-immune chicken serum containing E.necatrix-specific antibodies. Approximately 680 protein spots for E.necatrix sporozoite were detected by 2-DE with silver staining, where 98 spots were cross-reacted with the E. necatrix-specific immune sera. Out of the 56 spots that were selected for MALDI-TOF-MS/MS analysis, 50 unique proteins were identified using the MASCOT software, 8 proteins were identified as known E.necatrix proteins and the rest were all putative proteins. These proteins have a wide range of known or predicted structures, cellular locations and functions, including proteins in category nuclear location & function, multifunctional- or multifunctional motifs-containing proteins, cellular transport and structure-related proteins, proteins of enzymatic activities, motor proteins-related, cell surface and organelle-related proteins. These new findings will enhance our understandings of parasite immunogenicity and immune evasion mechanisms of E. necatrix and facilitate the discovery phase of highly effective vaccine candidates.
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Affiliation(s)
- Guanggang Qu
- Binzhou Animal Science and Veterinary Medicine Academy, Binzhou, 256600, Shandong, PR China
| | - Zhiyang Xu
- The Analysis Center, Nanjing Medical University, Nanjing, 211166, Jiangsu, PR China
| | - Wenbin Tuo
- Animal Parasitic Diseases Laboratory, Agricultural Research Service, United States Department of Agriculture, Beltsville, MD, 20705, USA
| | - Charles Li
- Animal Bioscience and Biotechnology Laboratory, Agricultural Research Service, United States Department of Agriculture, Beltsville, MD, 20705, United States
| | - Hyun Lillehoj
- Animal Bioscience and Biotechnology Laboratory, Agricultural Research Service, United States Department of Agriculture, Beltsville, MD, 20705, United States
| | - Gen Wan
- Jiangxi Provincial Key Laboratory for Animal Health, College of Animal Science and Technology, Jiangxi Agricultural University, Nanchang, 330045, Jiangxi, PR China
| | - Haiwei Gong
- Jiangxi Provincial Key Laboratory for Animal Health, College of Animal Science and Technology, Jiangxi Agricultural University, Nanchang, 330045, Jiangxi, PR China
| | - Jinxin Huang
- Jiangxi Provincial Key Laboratory for Animal Health, College of Animal Science and Technology, Jiangxi Agricultural University, Nanchang, 330045, Jiangxi, PR China
| | - Guichuan Tian
- Jiangxi Provincial Key Laboratory for Animal Health, College of Animal Science and Technology, Jiangxi Agricultural University, Nanchang, 330045, Jiangxi, PR China
| | - Shanxin Li
- Jiangxi Provincial Key Laboratory for Animal Health, College of Animal Science and Technology, Jiangxi Agricultural University, Nanchang, 330045, Jiangxi, PR China
| | - Yuxin Liu
- Jiangxi Provincial Key Laboratory for Animal Health, College of Animal Science and Technology, Jiangxi Agricultural University, Nanchang, 330045, Jiangxi, PR China
| | - Liheng Liu
- Jiangxi Provincial Key Laboratory for Animal Health, College of Animal Science and Technology, Jiangxi Agricultural University, Nanchang, 330045, Jiangxi, PR China.
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13
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Lyons SP, Greiner EC, Cressey LE, Adamo ME, Kettenbach AN. Regulation of PP2A, PP4, and PP6 holoenzyme assembly by carboxyl-terminal methylation. Sci Rep 2021; 11:23031. [PMID: 34845248 PMCID: PMC8630191 DOI: 10.1038/s41598-021-02456-z] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2021] [Accepted: 11/15/2021] [Indexed: 12/16/2022] Open
Abstract
The family of Phosphoprotein Phosphatases (PPPs) is responsible for most cellular serine and threonine dephosphorylation. PPPs achieve substrate specificity and selectivity by forming multimeric holoenzymes. PPP holoenzyme assembly is tightly controlled, and changes in the cellular repertoire of PPPs are linked to human disease, including cancer and neurodegeneration. For PP2A, PP4, and PP6, holoenzyme formation is in part regulated by carboxyl (C)-terminal methyl-esterification (often referred to as "methylation"). Here, we use mass spectrometry-based proteomics, methylation-ablating mutations, and genome editing to elucidate the role of C-terminal methylation on PP2A, PP4, and PP6 holoenzyme assembly. We find that the catalytic subunits of PP2A, PP4, and PP6 are frequently methylated in cancer cells and that deletion of the C-terminal leucine faithfully recapitulates loss of methylation. We observe that loss of PP2A methylation consistently reduced B55, B56, and B72 regulatory subunit binding in cancer and non-transformed cell lines. However, Striatin subunit binding is only affected in non-transformed cells. For PP4, we find that PP4R1 and PP4R3β bind in a methylation-dependent manner. Intriguingly, loss of methylation does not affect PP6 holoenzymes. Our analyses demonstrate in an unbiased, comprehensive, and isoform-specific manner the crucial regulatory function of endogenous PPP methylation in transformed and non-transformed cell lines.
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Affiliation(s)
- Scott P Lyons
- Department of Biochemistry and Cell Biology, Geisel School of Medicine at Dartmouth, Hanover, NH, USA
| | | | | | | | - Arminja N Kettenbach
- Department of Biochemistry and Cell Biology, Geisel School of Medicine at Dartmouth, Hanover, NH, USA.
- Norris Cotton Cancer Center, Lebanon, NH, USA.
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14
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Wu Q, Zhou D, Wu R, Shi R, Shen X, Jin N, Gu J, Gu JH, Liu F, Chu D. Excess folic acid supplementation before and during pregnancy and lactation activates β-catenin in the brain of male mouse offspring. Brain Res Bull 2021; 178:133-143. [PMID: 34808323 DOI: 10.1016/j.brainresbull.2021.11.008] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2021] [Revised: 11/03/2021] [Accepted: 11/15/2021] [Indexed: 02/07/2023]
Abstract
Folic acid (FA) supplementation in early pregnancy is recommended to protect against birth defects. But excess FA has exhibited neurodevelopmental toxicity. We previously reported that the mice treated with 2.5-fold the dietary requirement of FA one week before mating and throughout pregnancy and lactation displayed abnormal behaviors in the offspring. Here we found the levels of non-phosphorylated β-catenin (active) were increased in the brains of weaning and adult FA-exposed offspring. Meanwhile, demethylation of protein phosphatase 2 A catalytic subunit (PP2Ac), which suppresses its enzyme activity in regulatory subunit dependent manner, was significantly inhibited. Among the upstream regulators of β-catenin, PI3K/Akt/GSK-3β but not Wnt signaling was stimulated in FA-exposed brains only at weaning. In mouse neuroblastoma N2a cells, knockdown of PP2Ac or leucine carboxyl methyltransferase-1 (LCMT-1), or overexpression of PP2Ac methylation-deficient mutant decreased β-catenin dephosphorylation. These results suggest that excess FA may activate β-catenin via suppressing PP2Ac demethylation, providing a novel mechanism for the influence of FA on neurodevelopment.
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Affiliation(s)
- Qian Wu
- Key Laboratory of Neuroregeneration of Jiangsu and Ministry of Education, NMPA Key Laboratory for Research and Evaluation of Tissue Engineering Technology Products, Co-innovation Center of Neuroregeneration, Nantong University, 226001 Nantong, China
| | - Dingwei Zhou
- Key Laboratory of Neuroregeneration of Jiangsu and Ministry of Education, NMPA Key Laboratory for Research and Evaluation of Tissue Engineering Technology Products, Co-innovation Center of Neuroregeneration, Nantong University, 226001 Nantong, China
| | - Ruozhen Wu
- Key Laboratory of Neuroregeneration of Jiangsu and Ministry of Education, NMPA Key Laboratory for Research and Evaluation of Tissue Engineering Technology Products, Co-innovation Center of Neuroregeneration, Nantong University, 226001 Nantong, China
| | - Ruirui Shi
- Department of Clinical Pharmacy, Affiliated Maternity and Child Health Care Hospital of Nantong University, Nantong University, 226018 Nantong, China
| | - Xin Shen
- Key Laboratory of Neuroregeneration of Jiangsu and Ministry of Education, NMPA Key Laboratory for Research and Evaluation of Tissue Engineering Technology Products, Co-innovation Center of Neuroregeneration, Nantong University, 226001 Nantong, China
| | - Nana Jin
- Key Laboratory of Neuroregeneration of Jiangsu and Ministry of Education, NMPA Key Laboratory for Research and Evaluation of Tissue Engineering Technology Products, Co-innovation Center of Neuroregeneration, Nantong University, 226001 Nantong, China
| | - Jianlan Gu
- Department of Biochemistry and Molecular Biology, School of Medicine, Nantong University, 226001 Nantong, China
| | - Jin-Hua Gu
- Department of Clinical Pharmacy, Affiliated Maternity and Child Health Care Hospital of Nantong University, Nantong University, 226018 Nantong, China.
| | - Fei Liu
- Department of Neurochemistry, Inge Grundke-Iqbal Research Floor, New York State Institute for Basic Research in Developmental Disabilities, Staten Island, NY 10314, United States.
| | - Dandan Chu
- Key Laboratory of Neuroregeneration of Jiangsu and Ministry of Education, NMPA Key Laboratory for Research and Evaluation of Tissue Engineering Technology Products, Co-innovation Center of Neuroregeneration, Nantong University, 226001 Nantong, China.
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15
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Chen L, Kashina A. Post-translational Modifications of the Protein Termini. Front Cell Dev Biol 2021; 9:719590. [PMID: 34395449 PMCID: PMC8358657 DOI: 10.3389/fcell.2021.719590] [Citation(s) in RCA: 31] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2021] [Accepted: 06/30/2021] [Indexed: 12/12/2022] Open
Abstract
Post-translational modifications (PTM) involve enzyme-mediated covalent addition of functional groups to proteins during or after synthesis. These modifications greatly increase biological complexity and are responsible for orders of magnitude change between the variety of proteins encoded in the genome and the variety of their biological functions. Many of these modifications occur at the protein termini, which contain reactive amino- and carboxy-groups of the polypeptide chain and often are pre-primed through the actions of cellular machinery to expose highly reactive residues. Such modifications have been known for decades, but only a few of them have been functionally characterized. The vast majority of eukaryotic proteins are N- and C-terminally modified by acetylation, arginylation, tyrosination, lipidation, and many others. Post-translational modifications of the protein termini have been linked to different normal and disease-related processes and constitute a rapidly emerging area of biological regulation. Here we highlight recent progress in our understanding of post-translational modifications of the protein termini and outline the role that these modifications play in vivo.
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Affiliation(s)
| | - Anna Kashina
- Department of Biomedical Sciences, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, PA, United States
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16
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Yoshie M, Ishida A, Ohashi H, Nakachi N, Azumi M, Tamura K. Stathmin dynamics modulate the activity of eribulin in breast cancer cells. Pharmacol Res Perspect 2021; 9:e00786. [PMID: 34176226 PMCID: PMC8236080 DOI: 10.1002/prp2.786] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2020] [Revised: 03/24/2021] [Accepted: 04/11/2021] [Indexed: 12/02/2022] Open
Abstract
Stathmin, a phosphoprotein that modulates microtubule dynamics, is highly expressed in breast cancer cells. Eribulin, a microtubule‐depolymerizing agent, is used to treat patients with advanced breast cancer. However, the detailed mechanisms underlying the action of eribulin during microtubule catastrophe, and the interaction between eribulin and stathmin dynamics, remain unclear. Here, we investigated the role of stathmin in the antiproliferative activity of eribulin in breast cancer cells. Eribulin induced phosphorylation of stathmin in MCF7 and MDA‐MB‐231 cells; this was attenuated by an inhibitor of protein kinase A (H89) and an inhibitor of Ca2+/calmodulin‐dependent kinase II (KN62). In addition, expression of phosphorylated stathmin was reduced by the protein phosphatase PP2A activator FTY720 but increased by the PP2A inhibitor okadaic acid. Of note, expression of PP2A subunits in eribulin‐treated cells decreased, although eribulin did not affect the phosphatase activity of recombinant PP2A directly. Furthermore, the antiproliferative effect of eribulin was stronger in stathmin‐overexpressing cells. These results suggest that stathmin dynamics are closely associated with the antiproliferative effects of eribulin and stathmin is a possible biomarker for predicting the therapeutic effects of eribulin in breast cancer patients.
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Affiliation(s)
- Mikihiro Yoshie
- Department of Endocrine Pharmacology, Tokyo University of Pharmacy and Life Sciences, Hachioji, Japan
| | - Akari Ishida
- Department of Endocrine Pharmacology, Tokyo University of Pharmacy and Life Sciences, Hachioji, Japan
| | - Haruka Ohashi
- Department of Endocrine Pharmacology, Tokyo University of Pharmacy and Life Sciences, Hachioji, Japan
| | - Nami Nakachi
- Department of Endocrine Pharmacology, Tokyo University of Pharmacy and Life Sciences, Hachioji, Japan
| | - Mana Azumi
- Department of Endocrine Pharmacology, Tokyo University of Pharmacy and Life Sciences, Hachioji, Japan
| | - Kazuhiro Tamura
- Department of Endocrine Pharmacology, Tokyo University of Pharmacy and Life Sciences, Hachioji, Japan
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17
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Guo R, Ning Y, Ma Y, Lin Q, Shen N, Shi P. Long non-coding RNA HOTAIR/microRNA-761 sponge regulates PPME1 and further influences cell biological functions in thyroid carcinoma. Laryngoscope Investig Otolaryngol 2021; 6:438-445. [PMID: 34195365 PMCID: PMC8223458 DOI: 10.1002/lio2.593] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2021] [Revised: 05/14/2021] [Accepted: 05/17/2021] [Indexed: 11/25/2022] Open
Abstract
BACKGROUND Most well-differentiated thyroid carcinomas display good therapeutic outcomes, but there are still some patients who are not sensitive to the general treatments lose their treatment opportunities. Thus, it is important to understand the molecular mechanisms that cause thyroid carcinoma, so as to find effective diagnostic and therapeutic targets. AIM OF THE STUDY To explore the role of homeobox transcript antisense RNA (HOTAIR) in thyroid carcinoma through protein phosphatase methylesterase 1 (PPME1) by sponging microRNA 761 (miR-761). METHODS The regulation network amongst HOTAIR, miR-761 and PPME1 was predicted by online sources. RT-PCR was conducted to evaluate the expression of HOTAIR and miR-761 in tumor tissues. Clinical data was collected and analyzed by Chi-square test. Cell apoptosis and proliferation was evaluated using three types of cancer cells (HTh-7, CAL-62, BCPAP) after treated with si-HOTAIR and miR-761inhibitor. The binding site among HOTAIR, miR-761 and PPME1 was verified by dual luciferase reporter assay. PPME1 expression was measured after HOTAIR and miR-761 were suppressed by western blot. Survival time was measured in nude mice using log-rank test. RESULTS HOTAIR was expressed to a significantly greater extent than miR-761 in thyroid tumor tissues (P < .001). miR-761 and PPME1 were negatively correlated (coef = -1.91, P < .001). HOTAIR competitively binds to miR-761 and miR-761 directly targets PPME1. HOTAIR was highly correlated with TNM (χ 2 = 5.797, P = .016), tumor size (χ 2 = 7.955, P = .005) and lymphatic metastasis (χ 2 = 6.0, P = .014). HOTAIR promoted cell proliferation and inhibited cell apoptosis, whereas miR-761 did not. HOTAIR elevated and miR-761 suppressed PPME1 expression. HOTAIR expression appears to affect the survival time in vivo. CONCLUSION HOTAIR regulated thyroid cancer cells by binding to miR-761 through PPME1.
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Affiliation(s)
- Runsheng Guo
- Department of General SurgeryJiading District Central Hospital Affiliated to Shanghai University of Medicine & Health SciencesShanghaiChina
| | - Yong Ning
- Department of General SurgeryJiading District Central Hospital Affiliated to Shanghai University of Medicine & Health SciencesShanghaiChina
| | - Ye Ma
- Department of General SurgeryJiading District Central Hospital Affiliated to Shanghai University of Medicine & Health SciencesShanghaiChina
| | - Qianhuang Lin
- Department of General SurgeryJiading District Central Hospital Affiliated to Shanghai University of Medicine & Health SciencesShanghaiChina
| | - Na Shen
- Department of Otolaryngology, Zhongshan HospitalFudan UniversityShanghaiChina
| | - Peidong Shi
- Department of General SurgeryJiading District Central Hospital Affiliated to Shanghai University of Medicine & Health SciencesShanghaiChina
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18
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Thapa C, Roivas P, Haataja T, Permi P, Pentikäinen U. The Interaction Mechanism of Intrinsically Disordered PP2A Inhibitor Proteins ARPP-16 and ARPP-19 With PP2A. Front Mol Biosci 2021; 8:650881. [PMID: 33842550 PMCID: PMC8032985 DOI: 10.3389/fmolb.2021.650881] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2021] [Accepted: 03/03/2021] [Indexed: 12/01/2022] Open
Abstract
Protein phosphatase 2A (PP2A) activity is critical for maintaining normal physiological cellular functions. PP2A is inhibited by endogenous inhibitor proteins in several pathological conditions including cancer. A PP2A inhibitor protein, ARPP-19, has recently been connected to several human cancer types. Accordingly, the knowledge about ARPP-19—PP2A inhibition mechanism is crucial for the understanding the disease development and the therapeutic targeting of ARPP-19—PP2A. Here, we show the first structural characterization of ARPP-19, and its splice variant ARPP-16 using NMR spectroscopy, and SAXS. The results reveal that both ARPP proteins are intrinsically disordered but contain transient secondary structure elements. The interaction mechanism of ARPP-16/19 with PP2A was investigated using microscale thermophoresis and NMR spectroscopy. Our results suggest that ARPP—PP2A A-subunit interaction is mediated by linear motif and has modest affinity whereas, the interaction of ARPPs with B56-subunit is weak and transient. Like many IDPs, ARPPs are promiscuous binders that transiently interact with PP2A A- and B56 subunits using multiple interaction motifs. In summary, our results provide a good starting point for future studies and development of therapeutics that block ARPP-PP2A interactions.
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Affiliation(s)
- Chandan Thapa
- Department of Biological and Environmental Science and Nanoscience Center, University of Jyvaskyla, Jyvaskyla, Finland.,Institute of Biomedicine, University of Turku, Turku, Finland.,Turku BioScience Centre, University of Turku, Turku, Finland
| | - Pekka Roivas
- Institute of Biomedicine, University of Turku, Turku, Finland.,Turku BioScience Centre, University of Turku, Turku, Finland
| | - Tatu Haataja
- Department of Biological and Environmental Science and Nanoscience Center, University of Jyvaskyla, Jyvaskyla, Finland.,Institute of Biomedicine, University of Turku, Turku, Finland.,Turku BioScience Centre, University of Turku, Turku, Finland
| | - Perttu Permi
- Department of Biological and Environmental Science and Nanoscience Center, University of Jyvaskyla, Jyvaskyla, Finland.,Department of Chemistry and Nanoscience Center, University of Jyvaskyla, Jyvaskyla, Finland
| | - Ulla Pentikäinen
- Institute of Biomedicine, University of Turku, Turku, Finland.,Turku BioScience Centre, University of Turku, Turku, Finland
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19
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Gnanaprakash M, Staniszewski A, Zhang H, Pitstick R, Kavanaugh MP, Arancio O, Nicholls RE. Leucine Carboxyl Methyltransferase 1 Overexpression Protects Against Cognitive and Electrophysiological Impairments in Tg2576 APP Transgenic Mice. J Alzheimers Dis 2021; 79:1813-1829. [PMID: 33459709 PMCID: PMC8203222 DOI: 10.3233/jad-200462] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Background: The serine/threonine protein phosphatase, PP2A, is thought to play a central role in the molecular pathogenesis of Alzheimer’s disease (AD), and the activity and substrate specificity of PP2A is regulated, in part, through methylation and demethylation of its catalytic subunit. Previously, we found that transgenic overexpression of the PP2A methyltransferase, LCMT-1, or the PP2A methylesterase, PME-1, altered the sensitivity of mice to impairments caused by acute exposure to synthetic oligomeric amyloid-β (Aβ). Objective: Here we sought to test the possibility that these molecules also controlled sensitivity to impairments caused by chronically elevated levels of Aβ produced in vivo. Methods: To do this, we examined the effects of transgenic LCMT-1, or PME-1 overexpression on cognitive and electrophysiological impairments caused by chronic overexpression of mutant human APP in Tg2576 mice. Results: We found that LCMT-1 overexpression prevented impairments in short-term spatial memory and synaptic plasticity in Tg2576 mice, without altering APP expression or soluble Aβ levels. While the magnitude of the effects of PME-1 overexpression in Tg2576 mice was small and potentially confounded by the emergence of non-cognitive impairments, Tg2576 mice that overexpressed PME-1 showed a trend toward earlier onset and/or increased severity of cognitive and electrophysiological impairments. Conclusion: These data suggest that the PP2A methyltransferase, LCMT-1, and the PP2A methylesterase, PME-1, may participate in the molecular pathogenesis of AD by regulating sensitivity to the pathogenic effects of chronically elevated levels of Aβ.
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Affiliation(s)
- Madhumathi Gnanaprakash
- Department of Pathology and Cell Biology, Columbia University, New York, NY, USA.,The Taub Institute for Research on Alzheimer's Disease and the Aging Brain, Columbia University, New York, NY, USA
| | - Agnieszka Staniszewski
- Department of Pathology and Cell Biology, Columbia University, New York, NY, USA.,The Taub Institute for Research on Alzheimer's Disease and the Aging Brain, Columbia University, New York, NY, USA
| | - Hong Zhang
- Department of Pathology and Cell Biology, Columbia University, New York, NY, USA.,The Taub Institute for Research on Alzheimer's Disease and the Aging Brain, Columbia University, New York, NY, USA
| | | | | | - Ottavio Arancio
- Department of Pathology and Cell Biology, Columbia University, New York, NY, USA.,The Taub Institute for Research on Alzheimer's Disease and the Aging Brain, Columbia University, New York, NY, USA.,Department of Medicine, Columbia University, New York, NY, USA
| | - Russell E Nicholls
- Department of Pathology and Cell Biology, Columbia University, New York, NY, USA.,The Taub Institute for Research on Alzheimer's Disease and the Aging Brain, Columbia University, New York, NY, USA
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20
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Interaction between Parkin and α-Synuclein in PARK2-Mediated Parkinson's Disease. Cells 2021; 10:cells10020283. [PMID: 33572534 PMCID: PMC7911026 DOI: 10.3390/cells10020283] [Citation(s) in RCA: 31] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2020] [Revised: 01/25/2021] [Accepted: 01/26/2021] [Indexed: 12/12/2022] Open
Abstract
Parkin and α-synuclein are two key proteins involved in the pathophysiology of Parkinson's disease (PD). Neurotoxic alterations of α-synuclein that lead to the formation of toxic oligomers and fibrils contribute to PD through synaptic dysfunction, mitochondrial impairment, defective endoplasmic reticulum and Golgi function, and nuclear dysfunction. In half of the cases, the recessively inherited early-onset PD is caused by loss of function mutations in the PARK2 gene that encodes the E3-ubiquitin ligase, parkin. Parkin is involved in the clearance of misfolded and aggregated proteins by the ubiquitin-proteasome system and regulates mitophagy and mitochondrial biogenesis. PARK2-related PD is generally thought not to be associated with Lewy body formation although it is a neuropathological hallmark of PD. In this review article, we provide an overview of post-mortem neuropathological examinations of PARK2 patients and present the current knowledge of a functional interaction between parkin and α-synuclein in the regulation of protein aggregates including Lewy bodies. Furthermore, we describe prevailing hypotheses about the formation of intracellular micro-aggregates (synuclein inclusions) that might be more likely than Lewy bodies to occur in PARK2-related PD. This information may inform future studies aiming to unveil primary signaling processes involved in PD and related neurodegenerative disorders.
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21
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Nasa I, Kettenbach AN. Effects of carboxyl-terminal methylation on holoenzyme function of the PP2A subfamily. Biochem Soc Trans 2020; 48:2015-2027. [PMID: 33125487 PMCID: PMC8380034 DOI: 10.1042/bst20200177] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2020] [Revised: 09/14/2020] [Accepted: 09/16/2020] [Indexed: 01/07/2023]
Abstract
Phosphoprotein Phosphatases (PPPs) are enzymes highly conserved from yeast and human and catalyze the majority of the serine and threonine dephosphorylation in cells. To achieve substrate specificity and selectivity, PPPs form multimeric holoenzymes consisting of catalytic, structural/scaffolding, and regulatory subunits. For the Protein Phosphatase 2A (PP2A)-subfamily of PPPs, holoenzyme assembly is at least in part regulated by an unusual carboxyl-terminal methyl-esterification, commonly referred to as 'methylation'. Carboxyl-terminal methylation is catalyzed by Leucine carboxyl methyltransferase-1 (LCMT1) that utilizes S-adenosyl-methionine (SAM) as the methyl donor and removed by protein phosphatase methylesterase 1 (PME1). For PP2A, methylation dictates regulatory subunit selection and thereby downstream phosphorylation signaling. Intriguingly, there are four families of PP2A regulatory subunits, each exhibiting different levels of methylation sensitivity. Thus, changes in PP2A methylation stoichiometry alters the complement of PP2A holoenzymes in cells and creates distinct modes of kinase opposition. Importantly, selective inactivation of PP2A signaling through the deregulation of methylation is observed in several diseases, most prominently Alzheimer's disease (AD). In this review, we focus on how carboxyl-terminal methylation of the PP2A subfamily (PP2A, PP4, and PP6) regulates holoenzyme function and thereby phosphorylation signaling, with an emphasis on AD.
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Affiliation(s)
- Isha Nasa
- Department of Biochemistry and Cell Biology, Geisel School of Medicine at Dartmouth College, Hanover, NH, U.S.A
- Norris Cotton Cancer Center, Dartmouth-Hitchcock Medical Center at Dartmouth, Lebanon, NH, U.S.A
| | - Arminja N Kettenbach
- Department of Biochemistry and Cell Biology, Geisel School of Medicine at Dartmouth College, Hanover, NH, U.S.A
- Norris Cotton Cancer Center, Dartmouth-Hitchcock Medical Center at Dartmouth, Lebanon, NH, U.S.A
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22
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Bheri M, Mahiwal S, Sanyal SK, Pandey GK. Plant protein phosphatases: What do we know about their mechanism of action? FEBS J 2020; 288:756-785. [PMID: 32542989 DOI: 10.1111/febs.15454] [Citation(s) in RCA: 33] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2020] [Revised: 05/27/2020] [Accepted: 06/09/2020] [Indexed: 12/30/2022]
Abstract
Protein phosphorylation is a major reversible post-translational modification. Protein phosphatases function as 'critical regulators' in signaling networks through dephosphorylation of proteins, which have been phosphorylated by protein kinases. A large understanding of their working has been sourced from animal systems rather than the plant or the prokaryotic systems. The eukaryotic protein phosphatases include phosphoprotein phosphatases (PPP), metallo-dependent protein phosphatases (PPM), protein tyrosine (Tyr) phosphatases (PTP), and aspartate (Asp)-dependent phosphatases. The PPP and PPM families are serine(Ser)/threonine(Thr)-specific phosphatases (STPs), while PTP family is Tyr specific. Dual-specificity phosphatases (DsPTPs/DSPs) dephosphorylate Ser, Thr, and Tyr residues. PTPs lack sequence homology with STPs, indicating a difference in catalytic mechanisms, while the PPP and PPM families share a similar structural fold indicating a common catalytic mechanism. The catalytic cysteine (Cys) residue in the conserved HCX5 R active site motif of the PTPs acts as a nucleophile during hydrolysis. The PPP members require metal ions, which coordinate the phosphate group of the substrate, followed by a nucleophilic attack by a water molecule and hydrolysis. The variable holoenzyme assembly of protein phosphatase(s) and the overlap with other post-translational modifications like acetylation and ubiquitination add to their complexity. Though their functional characterization is extensively reported in plants, the mechanistic nature of their action is still being explored by researchers. In this review, we exclusively overview the plant protein phosphatases with an emphasis on their mechanistic action as well as structural characteristics.
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Affiliation(s)
- Malathi Bheri
- Department of Plant Molecular Biology, University of Delhi South Campus, New Delhi, India
| | - Swati Mahiwal
- Department of Plant Molecular Biology, University of Delhi South Campus, New Delhi, India
| | - Sibaji K Sanyal
- Department of Plant Molecular Biology, University of Delhi South Campus, New Delhi, India
| | - Girdhar K Pandey
- Department of Plant Molecular Biology, University of Delhi South Campus, New Delhi, India
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23
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Leonard D, Huang W, Izadmehr S, O'Connor CM, Wiredja DD, Wang Z, Zaware N, Chen Y, Schlatzer DM, Kiselar J, Vasireddi N, Schüchner S, Perl AL, Galsky MD, Xu W, Brautigan DL, Ogris E, Taylor DJ, Narla G. Selective PP2A Enhancement through Biased Heterotrimer Stabilization. Cell 2020; 181:688-701.e16. [PMID: 32315618 DOI: 10.1016/j.cell.2020.03.038] [Citation(s) in RCA: 85] [Impact Index Per Article: 21.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2019] [Revised: 12/04/2019] [Accepted: 03/17/2020] [Indexed: 12/15/2022]
Abstract
Impairment of protein phosphatases, including the family of serine/threonine phosphatases designated PP2A, is essential for the pathogenesis of many diseases, including cancer. The ability of PP2A to dephosphorylate hundreds of proteins is regulated by over 40 specificity-determining regulatory "B" subunits that compete for assembly and activation of heterogeneous PP2A heterotrimers. Here, we reveal how a small molecule, DT-061, specifically stabilizes the B56α-PP2A holoenzyme in a fully assembled, active state to dephosphorylate selective substrates, such as its well-known oncogenic target, c-Myc. Our 3.6 Å structure identifies molecular interactions between DT-061 and all three PP2A subunits that prevent dissociation of the active enzyme and highlight inherent mechanisms of PP2A complex assembly. Thus, our findings provide fundamental insights into PP2A complex assembly and regulation, identify a unique interfacial stabilizing mode of action for therapeutic targeting, and aid in the development of phosphatase-based therapeutics tailored against disease specific phospho-protein targets.
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Affiliation(s)
- Daniel Leonard
- Department of Pathology, Case Western Reserve University School of Medicine, Cleveland, OH 44106, USA; Cleveland Clinic Lerner College of Medicine, Case Western Reserve University, Cleveland, OH 44106, USA
| | - Wei Huang
- Department of Pharmacology, Case Western Reserve University School of Medicine, Cleveland, OH 44106, USA
| | - Sudeh Izadmehr
- Division of Hematology and Medical Oncology, Department of Medicine, Tisch Cancer Institute, Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA; Department of Pathology, Molecular and Cell-Based Medicine, Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA
| | - Caitlin M O'Connor
- Division of Genetic Medicine, Department of Internal Medicine, University of Michigan, Ann Arbor, MI 48105, USA; Rogel Cancer Center, University of Michigan, Ann Arbor, MI 48109, USA
| | - Danica D Wiredja
- Department of Nutrition, Center for Proteomics and Bioinformatics, Case Western Reserve University, Cleveland, OH 44106, USA
| | - Zhizhi Wang
- Department of Biological Structure, University of Washington, Seattle, WA 98195, USA
| | - Nilesh Zaware
- Department of Pharmacological Sciences, Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA
| | - Yinghua Chen
- PEPCC Facility, Case Western Reserve University, 10900 Euclid Ave., Cleveland, OH 44106, USA
| | - Daniela M Schlatzer
- Department of Nutrition, Center for Proteomics and Bioinformatics, Case Western Reserve University, Cleveland, OH 44106, USA
| | - Janna Kiselar
- Department of Nutrition, Center for Proteomics and Bioinformatics, Case Western Reserve University, Cleveland, OH 44106, USA
| | - Nikhil Vasireddi
- Department of Biology, Case Western Reserve University, Cleveland, OH 44106, USA
| | - Stefan Schüchner
- Center for Medical Biochemistry, Max Perutz Labs, Medical University of Vienna, Dr. Bohr-Gasse 9/2, Vienna 1030, Austria
| | - Abbey L Perl
- Department of Pharmacology, Case Western Reserve University School of Medicine, Cleveland, OH 44106, USA
| | - Matthew D Galsky
- Division of Hematology and Medical Oncology, Department of Medicine, Tisch Cancer Institute, Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA
| | - Wenqing Xu
- Department of Biological Structure, University of Washington, Seattle, WA 98195, USA
| | - David L Brautigan
- Department of Microbiology, Immunology, and Cancer Biology, Center for Cell Signaling, University of Virginia, Charlottesville, VA 22903, USA
| | - Egon Ogris
- Center for Medical Biochemistry, Max Perutz Labs, Medical University of Vienna, Dr. Bohr-Gasse 9/2, Vienna 1030, Austria
| | - Derek J Taylor
- Department of Pharmacology, Case Western Reserve University School of Medicine, Cleveland, OH 44106, USA; Department of Biochemistry, Case Western Reserve University, Cleveland, OH 44106, USA.
| | - Goutham Narla
- Division of Genetic Medicine, Department of Internal Medicine, University of Michigan, Ann Arbor, MI 48105, USA; Rogel Cancer Center, University of Michigan, Ann Arbor, MI 48109, USA.
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24
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Frohner IE, Mudrak I, Kronlachner S, Schüchner S, Ogris E. Antibodies recognizing the C terminus of PP2A catalytic subunit are unsuitable for evaluating PP2A activity and holoenzyme composition. Sci Signal 2020; 13:13/616/eaax6490. [PMID: 31992581 DOI: 10.1126/scisignal.aax6490] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
The methyl-esterification of the C-terminal leucine of the protein phosphatase 2A (PP2A) catalytic (C) subunit is essential for the assembly of specific trimeric PP2A holoenzymes, and this region of the C subunit also contains two threonine and tyrosine phosphorylation sites. Most commercial antibodies-including the monoclonal antibody 1D6 that is part of a frequently used, commercial phosphatase assay kit-are directed toward the C terminus of the C subunit, raising questions as to their ability to recognize methylated and phosphorylated forms of the enzyme. Here, we tested several PP2A C antibodies, including monoclonal antibodies 1D6, 7A6, G-4, and 52F8 and the polyclonal antibody 2038 for their ability to specifically detect PP2A in its various modified forms, as well as to coprecipitate regulatory subunits. The tested antibodies preferentially recognized the nonmethylated form of the enzyme, and they did not coimmunoprecipitate trimeric holoenzymes containing the regulatory subunits B or B', an issue that precludes their use to monitor PP2A holoenzyme activity. Furthermore, some of the antibodies also recognized the phosphatase PP4, demonstrating a lack of specificity for PP2A. Together, these findings suggest that reinterpretation of the data generated by using these reagents is required.
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Affiliation(s)
- Ingrid E Frohner
- Center for Medical Biochemistry, Max Perutz Labs, Vienna BioCenter, Medical University of Vienna, Dr. Bohr-Gasse 9, A-1030 Vienna, Austria
| | - Ingrid Mudrak
- Center for Medical Biochemistry, Max Perutz Labs, Vienna BioCenter, Medical University of Vienna, Dr. Bohr-Gasse 9, A-1030 Vienna, Austria
| | - Stephanie Kronlachner
- Center for Medical Biochemistry, Max Perutz Labs, Vienna BioCenter, Medical University of Vienna, Dr. Bohr-Gasse 9, A-1030 Vienna, Austria
| | - Stefan Schüchner
- Center for Medical Biochemistry, Max Perutz Labs, Vienna BioCenter, Medical University of Vienna, Dr. Bohr-Gasse 9, A-1030 Vienna, Austria
| | - Egon Ogris
- Center for Medical Biochemistry, Max Perutz Labs, Vienna BioCenter, Medical University of Vienna, Dr. Bohr-Gasse 9, A-1030 Vienna, Austria.
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25
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Jin N, Shi R, Jiang Y, Chu D, Gong CX, Iqbal K, Liu F. Glycogen synthase kinase-3β suppresses the expression of protein phosphatase methylesterase-1 through β-catenin. Aging (Albany NY) 2019; 11:9672-9688. [PMID: 31714894 PMCID: PMC6874473 DOI: 10.18632/aging.102413] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2019] [Accepted: 10/28/2019] [Indexed: 12/19/2022]
Abstract
Protein phosphatase 2A (PP2A) is the major tau phosphatase. Its activity toward tau is regulated by the methylation of PP2A catalytic subunit (PP2Ac) at Leu309. Protein phosphatase methylesterase-1 (PME-1) demethylates PP2Ac and suppresses its activity. We previously found that glycogen synthase kinase-3β (GSK-3β) suppresses PME-1 expression. However, the underlying molecular mechanism is unknown. In the present study, we analyzed the promoter of PME-1 gene and found that human PME-1 promoter contains two lymphoid enhancer binding factor-1/T-cell factor (LEF1/TCF) cis-elements in which β-catenin serves as a co-activator. β-catenin acted on these two cis-elements and promoted PME-1 expression. GSK-3β phosphorylated β-catenin and suppressed its function in promoting PME-1 expression. Inhibition and activation of GSK-3β by PI3K-AKT pathway promoted and suppressed, respectively, PME-1 expression in primary cultured neurons, SH-SY5Y cells and in the mouse brain. These findings suggest that GSK-3β phosphorylates β-catenin and suppresses its function on PME-1 expression, resulting in an increase of PP2Ac methylation.
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Affiliation(s)
- Nana Jin
- Key Laboratory of Neuroregeneration of Jiangsu and Ministry of Education of China, Co-Innovation Center of Neuroregeneration, Nantong University, Nantong, Jiangsu 226001, China
| | - Ruirui Shi
- Key Laboratory of Neuroregeneration of Jiangsu and Ministry of Education of China, Co-Innovation Center of Neuroregeneration, Nantong University, Nantong, Jiangsu 226001, China
| | - Yanli Jiang
- Key Laboratory of Neuroregeneration of Jiangsu and Ministry of Education of China, Co-Innovation Center of Neuroregeneration, Nantong University, Nantong, Jiangsu 226001, China
| | - Dandan Chu
- Key Laboratory of Neuroregeneration of Jiangsu and Ministry of Education of China, Co-Innovation Center of Neuroregeneration, Nantong University, Nantong, Jiangsu 226001, China
| | - Cheng-Xin Gong
- Department of Neurochemistry, Inge Grundke-Iqbal Research Floor, New York State Institute for Basic Research in Developmental Disabilities, Staten Island, NY 10314, USA
| | - Khalid Iqbal
- Department of Neurochemistry, Inge Grundke-Iqbal Research Floor, New York State Institute for Basic Research in Developmental Disabilities, Staten Island, NY 10314, USA
| | - Fei Liu
- Department of Neurochemistry, Inge Grundke-Iqbal Research Floor, New York State Institute for Basic Research in Developmental Disabilities, Staten Island, NY 10314, USA
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26
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Yun S, Hu R, Schwaemmle ME, Scherer AN, Zhuang Z, Koleske AJ, Pallas DC, Schwartz MA. Integrin α5β1 regulates PP2A complex assembly through PDE4D in atherosclerosis. J Clin Invest 2019; 129:4863-4874. [PMID: 31408443 PMCID: PMC6819111 DOI: 10.1172/jci127692] [Citation(s) in RCA: 33] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2019] [Accepted: 08/07/2019] [Indexed: 12/15/2022] Open
Abstract
Fibronectin in the vascular wall promotes inflammatory activation of the endothelium during vascular remodeling and atherosclerosis. These effects are mediated in part by fibronectin binding to integrin α5, which recruits and activates phosphodiesterase 4D5 (PDE4D5) by inducing its dephosphorylation on an inhibitory site Ser651. Active PDE then hydrolyzes anti-inflammatory cAMP to facilitate inflammatory signaling. To test this model in vivo, we mutated the integrin binding site in PDE4D5 in mice. This mutation reduced endothelial inflammatory activation in athero-prone regions of arteries, and, in a hyperlipidemia model, reduced atherosclerotic plaque size while increasing markers of plaque stability. We then investigated the mechanism of PDE4D5 activation. Proteomics identified the PP2A regulatory subunit B55α as the factor recruiting PP2A to PDE4D5. The B55α-PP2A complex localized to adhesions and directly dephosphorylated PDE4D5. This interaction also unexpectedly stabilized the PP2A-B55α complex. The integrin-regulated, pro-atherosclerotic transcription factor Yap is also dephosphorylated and activated through this pathway. PDE4D5 therefore mediates matrix-specific regulation of EC phenotype via an unconventional adapter role, assembling and anchoring a multifunctional PP2A complex with other targets. These results are likely to have widespread consequences for control of cell function by integrins.
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Affiliation(s)
- Sanguk Yun
- Department of Internal Medicine, Yale Cardiovascular Research Center, and
| | - Rui Hu
- Department of Internal Medicine, Yale Cardiovascular Research Center, and
| | | | - Alexander N. Scherer
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, Connecticut, USA
| | - Zhenwu Zhuang
- Department of Internal Medicine, Yale Cardiovascular Research Center, and
| | - Anthony J. Koleske
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, Connecticut, USA
| | - David C. Pallas
- Department of Biochemistry, Emory University School of Medicine, Atlanta, Georgia, USA
| | - Martin A. Schwartz
- Department of Internal Medicine, Yale Cardiovascular Research Center, and
- Department of Biomedical Engineering, and
- Department of Cell Biology, Yale University, New Haven, Connecticut, USA
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27
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Brautigan DL, Shenolikar S. Protein Serine/Threonine Phosphatases: Keys to Unlocking Regulators and Substrates. Annu Rev Biochem 2019; 87:921-964. [PMID: 29925267 DOI: 10.1146/annurev-biochem-062917-012332] [Citation(s) in RCA: 110] [Impact Index Per Article: 22.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Protein serine/threonine phosphatases (PPPs) are ancient enzymes, with distinct types conserved across eukaryotic evolution. PPPs are segregated into types primarily on the basis of the unique interactions of PPP catalytic subunits with regulatory proteins. The resulting holoenzymes dock substrates distal to the active site to enhance specificity. This review focuses on the subunit and substrate interactions for PPP that depend on short linear motifs. Insights about these motifs from structures of holoenzymes open new opportunities for computational biology approaches to elucidate PPP networks. There is an expanding knowledge base of posttranslational modifications of PPP catalytic and regulatory subunits, as well as of their substrates, including phosphorylation, acetylation, and ubiquitination. Cross talk between these posttranslational modifications creates PPP-based signaling. Knowledge of PPP complexes, signaling clusters, as well as how PPPs communicate with each other in response to cellular signals should unlock the doors to PPP networks and signaling "clouds" that orchestrate and coordinate different aspects of cell physiology.
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Affiliation(s)
- David L Brautigan
- Center for Cell Signaling and Department of Microbiology, Immunology and Cancer Biology, University of Virginia School of Medicine, Charlottesville, Virginia 22908, USA;
| | - Shirish Shenolikar
- Signature Research Programs in Cardiovascular and Metabolic Disorders and Neuroscience and Behavioral Disorders, Duke-NUS Medical School, Singapore 169857
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28
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Elgenaidi IS, Spiers JP. Hypoxia modulates protein phosphatase 2A through HIF-1α dependent and independent mechanisms in human aortic smooth muscle cells and ventricular cardiomyocytes. Br J Pharmacol 2019; 176:1745-1763. [PMID: 30825189 DOI: 10.1111/bph.14648] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2018] [Revised: 02/05/2019] [Accepted: 02/13/2019] [Indexed: 12/18/2022] Open
Abstract
BACKGROUND AND PURPOSE Although protein phosphatases regulate multiple cellular functions, their modulation under hypoxia remains unclear. We investigated expression of the protein phosphatase system under normoxic/hypoxic conditions and the mechanism by which hypoxia alters protein phosphatase 2A (PP2A) activity. EXPERIMENTAL APPROACH Human cardiovascular cells were cultured in cell type specific media under normoxic or hypoxic conditions (1% O2 ). Effects on mRNA expression, phosphatase activity, post-translational modification, and involvement of hypoxia inducible factor 1α (HIF-1α) were assessed using RT-PCR, immunoblotting, an activity assay, and siRNA silencing. KEY RESULTS All components of the protein phosphatase system studied were expressed in each cell line. Hypoxia attenuated mRNA expression of the transcripts in a cell line- and time-dependent manner. In human aortic smooth muscle cells (HASMC) and AC16 cells, hypoxia decreased PP2Ac activity and mRNA expression without altering PP2Ac abundance. Hypoxia increased demethylated PP2Ac (DPP2Ac) and phosphatase methylesterase 1 (PME-1) abundance but decreased leucine carboxyl methyltransferase 1 (LCMT-1) abundance. HIF-1α siRNA prevented the hypoxia-mediated decrease in phosphatase activity and expression of the catalytic subunit of protein phosphatase 2A (PPP2CA), independently of altering pPP2Ac, DPP2Ac, LCMT-1, or PME-1 abundance. CONCLUSION AND IMPLICATIONS Cardiovascular cells express multiple components of the PP2A system. In HASMC and AC16 cells, hypoxia inhibits PP2A activity through HIF-1α-dependent and -independent mechanisms, with the latter being consistent with altered PP2A holoenzyme assembly. This indicates a complex inhibitory effect of hypoxia on the PP2A system, and highlights PP2A as a therapeutic target for diseases associated with dysregulated protein phosphorylation.
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Affiliation(s)
| | - James Paul Spiers
- Department of Pharmacology and Therapeutics, Trinity College Dublin, Dublin, Ireland
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29
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Raman D, Pervaiz S. Redox inhibition of protein phosphatase PP2A: Potential implications in oncogenesis and its progression. Redox Biol 2019; 27:101105. [PMID: 30686777 PMCID: PMC6859563 DOI: 10.1016/j.redox.2019.101105] [Citation(s) in RCA: 31] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2018] [Revised: 01/04/2019] [Accepted: 01/09/2019] [Indexed: 01/17/2023] Open
Abstract
Cellular processes are dictated by the active signaling of proteins relaying messages to regulate cell proliferation, apoptosis, signal transduction and cell communications. An intricate web of protein kinases and phosphatases are critical to the proper transmission of signals across such cascades. By governing 30–50% of all protein dephosphorylation in the cell, with prominent substrate proteins being key regulators of signaling cascades, the phosphatase PP2A has emerged as a celebrated player in various developmental and tumorigenic pathways, thereby posing as an attractive target for therapeutic intervention in various pathologies wherein its activity is deregulated. This review is mainly focused on refreshing our understanding of the structural and functional complexity that cocoons the PP2A phosphatase, and its expression in cancers. Additionally, we focus on its physiological regulation as well as into recent advents and strategies that have shown promise in countering the deregulation of the phosphatase through its targeted reactivation. Finally, we dwell upon one of the key regulators of PP2A in cancer cells-cellular redox status-its multifarious nature, and its integration into the reactome of PP2A, highlighting some of the significant impacts that ROS can inflict on the structural modifications and functional aspect of PP2A.
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Affiliation(s)
- Deepika Raman
- Department of Physiology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore
| | - Shazib Pervaiz
- Department of Physiology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore; Medical Science Cluster Cancer Program, Yong Loo Lin School of Medicine, National University of Singapore, Singapore; National University Cancer Institute, National University Health System, Singapore, Singapore; NUS Graduate School for Integrative Sciences and Engineering, National University of Singapore, Singapore.
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Reynhout S, Jansen S, Haesen D, van Belle S, de Munnik SA, Bongers EM, Schieving JH, Marcelis C, Amiel J, Rio M, Mclaughlin H, Ladda R, Sell S, Kriek M, Peeters-Scholte CM, Terhal PA, van Gassen KL, Verbeek N, Henry S, Scott Schwoerer J, Malik S, Revencu N, Ferreira CR, Macnamara E, Braakman HM, Brimble E, Ruzhnikov MR, Wagner M, Harrer P, Wieczorek D, Kuechler A, Tziperman B, Barel O, de Vries BB, Gordon CT, Janssens V, Vissers LE. De Novo Mutations Affecting the Catalytic Cα Subunit of PP2A, PPP2CA, Cause Syndromic Intellectual Disability Resembling Other PP2A-Related Neurodevelopmental Disorders. Am J Hum Genet 2019; 104:139-156. [PMID: 30595372 DOI: 10.1016/j.ajhg.2018.12.002] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2018] [Accepted: 12/06/2018] [Indexed: 12/11/2022] Open
Abstract
Type 2A protein phosphatases (PP2As) are highly expressed in the brain and regulate neuronal signaling by catalyzing phospho-Ser/Thr dephosphorylations in diverse substrates. PP2A holoenzymes comprise catalytic C-, scaffolding A-, and regulatory B-type subunits, which determine substrate specificity and physiological function. Interestingly, de novo mutations in genes encoding A- and B-type subunits have recently been implicated in intellectual disability (ID) and developmental delay (DD). We now report 16 individuals with mild to profound ID and DD and a de novo mutation in PPP2CA, encoding the catalytic Cα subunit. Other frequently observed features were severe language delay (71%), hypotonia (69%), epilepsy (63%), and brain abnormalities such as ventriculomegaly and a small corpus callosum (67%). Behavioral problems, including autism spectrum disorders, were reported in 47% of individuals, and three individuals had a congenital heart defect. PPP2CA de novo mutations included a partial gene deletion, a frameshift, three nonsense mutations, a single amino acid duplication, a recurrent mutation, and eight non-recurrent missense mutations. Functional studies showed complete PP2A dysfunction in four individuals with seemingly milder ID, hinting at haploinsufficiency. Ten other individuals showed mutation-specific biochemical distortions, including poor expression, altered binding to the A subunit and specific B-type subunits, and impaired phosphatase activity and C-terminal methylation. Four were suspected to have a dominant-negative mechanism, which correlated with severe ID. Two missense variants affecting the same residue largely behaved as wild-type in our functional assays. Overall, we found that pathogenic PPP2CA variants impair PP2A-B56(δ) functionality, suggesting that PP2A-related neurodevelopmental disorders constitute functionally converging ID syndromes.
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Ohama T. The multiple functions of protein phosphatase 6. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2019; 1866:74-82. [DOI: 10.1016/j.bbamcr.2018.07.015] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/27/2018] [Revised: 06/21/2018] [Accepted: 07/18/2018] [Indexed: 12/26/2022]
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Synergistic neuroprotection by coffee components eicosanoyl-5-hydroxytryptamide and caffeine in models of Parkinson's disease and DLB. Proc Natl Acad Sci U S A 2018; 115:E12053-E12062. [PMID: 30509990 PMCID: PMC6304960 DOI: 10.1073/pnas.1813365115] [Citation(s) in RCA: 41] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Hyperphosphorylated α-synuclein in Lewy bodies and Lewy neurites is a characteristic neuropathological feature of Parkinson's disease (PD) and Dementia with Lewy bodies (DLB). The catalytic subunit of the specific phosphatase, protein phosphatase 2A (PP2A) that dephosphorylates α-synuclein, is hypomethylated in these brains, thereby impeding the assembly of the active trimeric holoenzyme and reducing phosphatase activity. This phosphatase deficiency contributes to the accumulation of hyperphosphorylated α-synuclein, which tends to fibrillize more than unmodified α-synuclein. Eicosanoyl-5-hydroxytryptamide (EHT), a fatty acid derivative of serotonin found in coffee, inhibits the PP2A methylesterase so as to maintain PP2A in a highly active methylated state and mitigates the phenotype of α-synuclein transgenic (SynTg) mice. Considering epidemiologic and experimental evidence suggesting protective effects of caffeine in PD, we sought, in the present study, to test whether there is synergy between EHT and caffeine in models of α-synucleinopathy. Coadministration of these two compounds orally for 6 mo at doses that were individually ineffective in SynTg mice and in a striatal α-synuclein preformed fibril inoculation model resulted in reduced accumulation of phosphorylated α-synuclein, preserved neuronal integrity and function, diminished neuroinflammation, and improved behavioral performance. These indices were associated with increased levels of methylated PP2A in brain tissue. A similar profile of greater PP2A methylation and cytoprotection was found in SH-SY5Y cells cotreated with EHT and caffeine, but not with each compound alone. These findings suggest that these two components of coffee have synergistic effects in protecting the brain against α-synuclein-mediated toxicity through maintenance of PP2A in an active state.
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Yabe R, Tsuji S, Mochida S, Ikehara T, Usui T, Ohama T, Sato K. A stable association with PME-1 may be dispensable for PP2A demethylation - implications for the detection of PP2A methylation and immunoprecipitation. FEBS Open Bio 2018; 8:1486-1496. [PMID: 30186749 PMCID: PMC6120246 DOI: 10.1002/2211-5463.12485] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2017] [Revised: 06/06/2018] [Accepted: 06/27/2018] [Indexed: 12/03/2022] Open
Abstract
Reversible methyl-esterification (methylation) of Leu309 in the protein phosphatase 2A catalytic subunit (PP2Ac) is essential for proper biogenesis of the PP2A holoenzyme. Accumulating evidence links PP2Ac methylation to diseases, including cancer and neurodegenerative disorders. Protein phosphatase methyl-esterase (PME-1) specifically catalyzes PP2Ac demethylation. We demonstrate that PP2Ac is demethylated in cell extracts even at 0 °C unless prevented by a PME-1 methyl-esterase inhibitor. This promotes dissociation of PP2A heterotrimers with B55 or PR72 subunits, but not those with B56 subunits. These results reveal differential sensitivity of ABC heterotrimers to methylation status of the C subunit. Our study advocates caution when interpreting earlier findings, offers an effective protocol for preserving PP2A complexes, and reveals key distinctions between B subunits and their interactions with the AC core dimer of PP2A.
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Affiliation(s)
- Ryotaro Yabe
- Laboratory of Veterinary PharmacologyJoint Faculty of Veterinary MedicineYamaguchi UniversityJapan
| | - Shunya Tsuji
- Laboratory of Veterinary PharmacologyJoint Faculty of Veterinary MedicineYamaguchi UniversityJapan
| | - Satoru Mochida
- Priority Organization for Innovation and ExcellenceKumamoto UniversityJapan
| | - Tsuyoshi Ikehara
- Department of Food Science and TechnologyNational Fisheries UniversityShimonosekiJapan
| | - Tatsuya Usui
- Laboratory of Veterinary PharmacologyFaculty of AgricultureTokyo University of Agriculture and TechnologyFuchuJapan
| | - Takashi Ohama
- Laboratory of Veterinary PharmacologyJoint Faculty of Veterinary MedicineYamaguchi UniversityJapan
| | - Koichi Sato
- Laboratory of Veterinary PharmacologyJoint Faculty of Veterinary MedicineYamaguchi UniversityJapan
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Lee JA, Wang Z, Sambo D, Bunting KD, Pallas DC. Global loss of leucine carboxyl methyltransferase-1 causes severe defects in fetal liver hematopoiesis. J Biol Chem 2018; 293:9636-9650. [PMID: 29735529 PMCID: PMC6016458 DOI: 10.1074/jbc.ra118.002012] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2018] [Revised: 04/12/2018] [Indexed: 11/06/2022] Open
Abstract
Leucine carboxyl methyltransferase-1 (LCMT-1) methylates the C-terminal leucine α-carboxyl group of the catalytic subunits of the protein phosphatase 2A (PP2A) subfamily of protein phosphatases, PP2Ac, PP4c, and PP6c. LCMT-1 differentially regulates the formation and function of a subset of the heterotrimeric complexes that PP2A and PP4 form with their regulatory subunits. Global LCMT-1 knockout causes embryonic lethality in mice, but LCMT-1 function in development is unknown. In this study, we analyzed the effects of global LCMT-1 loss on embryonic development. LCMT-1 knockout causes loss of PP2Ac methylation, indicating that LCMT-1 is the sole PP2Ac methyltransferase. PP2A heterotrimers containing the Bα and Bδ B-type subunits are dramatically reduced in whole embryos, and the steady-state levels of PP2Ac and the PP2A structural A subunit are also down ∼30%. Strikingly, global loss of LCMT-1 causes severe defects in fetal hematopoiesis and usually death by embryonic day 16.5. Fetal livers of homozygous lcmt-1 knockout embryos display hypocellularity, elevated apoptosis, and greatly reduced numbers of hematopoietic stem and progenitor cell-enriched Kit+Lin-Sca1+ cells. The percent cycling cells and mitotic indices of WT and lcmt-1 knockout fetal liver cells are similar, suggesting that hypocellularity may be due to a combination of apoptosis and/or defects in specification, self-renewal, or survival of stem cells. Indicative of a possible intrinsic defect in stem cells, noncompetitive and competitive transplantation experiments reveal that lcmt-1 loss causes a severe multilineage hematopoietic repopulating defect. Therefore, this study reveals a novel role for LCMT-1 as a key player in fetal liver hematopoiesis.
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Affiliation(s)
- Jocelyn A Lee
- From the Department of Biochemistry, Winship Cancer Institute, the Biochemistry, Cell, and Developmental Graduate Program, and
| | - Zhengqi Wang
- the Aflac Cancer and Blood Disorders Center of Children's Healthcare of Atlanta, Department of Pediatrics, Winship Cancer Institute, Emory University School of Medicine, Atlanta, Georgia 30322
| | - Danielle Sambo
- From the Department of Biochemistry, Winship Cancer Institute, the Biochemistry, Cell, and Developmental Graduate Program, and
| | - Kevin D Bunting
- the Aflac Cancer and Blood Disorders Center of Children's Healthcare of Atlanta, Department of Pediatrics, Winship Cancer Institute, Emory University School of Medicine, Atlanta, Georgia 30322
| | - David C Pallas
- From the Department of Biochemistry, Winship Cancer Institute, the Biochemistry, Cell, and Developmental Graduate Program, and
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Tian H, Lu Y, Liu J, Liu W, Lu L, Duan C, Gao G, Yang H. Leucine Carboxyl Methyltransferase Downregulation and Protein Phosphatase Methylesterase Upregulation Contribute Toward the Inhibition of Protein Phosphatase 2A by α-Synuclein. Front Aging Neurosci 2018; 10:173. [PMID: 29950985 PMCID: PMC6008559 DOI: 10.3389/fnagi.2018.00173] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2018] [Accepted: 05/22/2018] [Indexed: 11/13/2022] Open
Abstract
The pathology of Parkinson's disease (PD) is characterized by intracellular neurofibrillary tangles of phosphorylated α-synuclein (α-syn). Protein phosphatase 2A (PP2A) is responsible for α-syn dephosphorylation. Previous work has demonstrated that α-syn can regulate PP2A activity. However, the mechanisms underlying α-syn regulation of PP2A activity are not well understood. In this study, we found that α-syn overexpression induced increased α-syn phosphorylation at serine 129 (Ser129), and PP2A inhibition, in vitro and in vivo. α-syn overexpression resulted in PP2A demethylation. This demethylation was mediated via downregulated leucine carboxyl methyltransferase (LCMT-1) expression, and upregulated protein phosphatase methylesterase (PME-1) expression. Furthermore, LCMT-1 overexpression, or PME-1 inhibition, reversed α-syn-induced increases in α-syn phosphorylation and apoptosis. In addition to post-translational modifications of the catalytic subunit, regulatory subunits are involved in the regulation of PP2A activity. We found that the levels of regulatory subunits which belong to the PPP2R2 subfamily, not the PPP2R5 subfamily, were downregulated in the examined brain regions of transgenic mice. Our work identifies a novel mechanism to explain how α-syn regulates PP2A activity, and provides the optimization of PP2A methylation as a new target for PD treatment.
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Affiliation(s)
- Hao Tian
- Department of Neurobiology Capital Medical University, Center of Parkinson's Disease Beijing Institute for Brain Disorders, Beijing Key Laboratory on Parkinson's Disease, Key Laboratory for Neurodegenerative Disease of the Ministry of Education, Beijing Center of Neural Regeneration and Repair, Beijing, China
| | - Yongquan Lu
- Department of Neurobiology Capital Medical University, Center of Parkinson's Disease Beijing Institute for Brain Disorders, Beijing Key Laboratory on Parkinson's Disease, Key Laboratory for Neurodegenerative Disease of the Ministry of Education, Beijing Center of Neural Regeneration and Repair, Beijing, China
| | - Jia Liu
- Department of Neurobiology Capital Medical University, Center of Parkinson's Disease Beijing Institute for Brain Disorders, Beijing Key Laboratory on Parkinson's Disease, Key Laboratory for Neurodegenerative Disease of the Ministry of Education, Beijing Center of Neural Regeneration and Repair, Beijing, China
| | - Weijin Liu
- Department of Neurobiology Capital Medical University, Center of Parkinson's Disease Beijing Institute for Brain Disorders, Beijing Key Laboratory on Parkinson's Disease, Key Laboratory for Neurodegenerative Disease of the Ministry of Education, Beijing Center of Neural Regeneration and Repair, Beijing, China
| | - Lingling Lu
- Department of Neurobiology Capital Medical University, Center of Parkinson's Disease Beijing Institute for Brain Disorders, Beijing Key Laboratory on Parkinson's Disease, Key Laboratory for Neurodegenerative Disease of the Ministry of Education, Beijing Center of Neural Regeneration and Repair, Beijing, China
| | - Chunli Duan
- Department of Neurobiology Capital Medical University, Center of Parkinson's Disease Beijing Institute for Brain Disorders, Beijing Key Laboratory on Parkinson's Disease, Key Laboratory for Neurodegenerative Disease of the Ministry of Education, Beijing Center of Neural Regeneration and Repair, Beijing, China
| | - Ge Gao
- Department of Neurobiology Capital Medical University, Center of Parkinson's Disease Beijing Institute for Brain Disorders, Beijing Key Laboratory on Parkinson's Disease, Key Laboratory for Neurodegenerative Disease of the Ministry of Education, Beijing Center of Neural Regeneration and Repair, Beijing, China
| | - Hui Yang
- Department of Neurobiology Capital Medical University, Center of Parkinson's Disease Beijing Institute for Brain Disorders, Beijing Key Laboratory on Parkinson's Disease, Key Laboratory for Neurodegenerative Disease of the Ministry of Education, Beijing Center of Neural Regeneration and Repair, Beijing, China
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Kim SY, Choi J, Lee DH, Park JH, Hwang YJ, Baek KH. PME-1 is regulated by USP36 in ERK and Akt signaling pathways. FEBS Lett 2018; 592:1575-1588. [PMID: 29577269 DOI: 10.1002/1873-3468.13039] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2018] [Revised: 03/12/2018] [Accepted: 03/14/2018] [Indexed: 12/13/2022]
Abstract
Deubiquitinating enzymes (DUBs) play an important role in the ubiquitin-proteasome system (UPS) by eliminating ubiquitins from substrates and inhibiting proteasomal degradation. Protein phosphatase methylesterase 1 (PME-1) inactivates protein phosphatase 2A (PP2A) and enhances the ERK and Akt signaling pathways, which increase cell proliferation and malignant cell transformation. In this study, we demonstrate that USP36 regulates PME-1 through its deubiquitinating enzyme activity. USP36 increases PME-1 stability, and depletion of USP36 decreases the PME-1 expression level. Furthermore, we demonstrate that USP36 promotes the ERK and Akt signaling pathways. In summary, it is suggested that USP36 regulates PME-1 as a DUB and participates in the ERK and Akt signaling pathways.
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Affiliation(s)
- Soo-Yeon Kim
- Department of Biomedical Science, CHA University, Seongnam-Si, Gyeonggi-Do, Korea
| | - Jihye Choi
- Department of Biomedical Science, CHA University, Seongnam-Si, Gyeonggi-Do, Korea
| | - Da-Hye Lee
- Department of Biomedical Science, CHA University, Seongnam-Si, Gyeonggi-Do, Korea
| | - Jun-Hyeok Park
- Department of Biomedical Science, CHA University, Seongnam-Si, Gyeonggi-Do, Korea
| | - Young-Jae Hwang
- Department of Biomedical Science, CHA University, Seongnam-Si, Gyeonggi-Do, Korea
| | - Kwang-Hyun Baek
- Department of Biomedical Science, CHA University, Seongnam-Si, Gyeonggi-Do, Korea
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Proteomic Identification of Heat Shock-Induced Danger Signals in a Melanoma Cell Lysate Used in Dendritic Cell-Based Cancer Immunotherapy. J Immunol Res 2018; 2018:3982942. [PMID: 29744371 PMCID: PMC5878886 DOI: 10.1155/2018/3982942] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2017] [Revised: 11/28/2017] [Accepted: 12/11/2017] [Indexed: 12/17/2022] Open
Abstract
Autologous dendritic cells (DCs) loaded with cancer cell-derived lysates have become a promising tool in cancer immunotherapy. During the last decade, we demonstrated that vaccination of advanced melanoma patients with autologous tumor antigen presenting cells (TAPCells) loaded with an allogeneic heat shock- (HS-) conditioned melanoma cell-derived lysate (called TRIMEL) is able to induce an antitumor immune response associated with a prolonged patient survival. TRIMEL provides not only a broad spectrum of potential melanoma-associated antigens but also danger signals that are crucial in the induction of a committed mature DC phenotype. However, potential changes induced by heat conditioning on the proteome of TRIMEL are still unknown. The identification of newly or differentially expressed proteins under defined stress conditions is relevant for understanding the lysate immunogenicity. Here, we characterized the proteomic profile of TRIMEL in response to HS treatment. A quantitative label-free proteome analysis of over 2800 proteins was performed, with 91 proteins that were found to be regulated by HS treatment: 18 proteins were overexpressed and 73 underexpressed. Additionally, 32 proteins were only identified in the HS-treated TRIMEL and 26 in non HS-conditioned samples. One protein from the overexpressed group and two proteins from the HS-exclusive group were previously described as potential damage-associated molecular patterns (DAMPs). Some of the HS-induced proteins, such as haptoglobin, could be also considered as DAMPs and candidates for further immunological analysis in the establishment of new putative danger signals with immunostimulatory functions.
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Kauko O, Westermarck J. Non-genomic mechanisms of protein phosphatase 2A (PP2A) regulation in cancer. Int J Biochem Cell Biol 2018; 96:157-164. [DOI: 10.1016/j.biocel.2018.01.005] [Citation(s) in RCA: 44] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2017] [Revised: 12/03/2017] [Accepted: 01/09/2018] [Indexed: 02/08/2023]
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39
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Park HJ, Lee KW, Oh S, Yan R, Zhang J, Beach TG, Adler CH, Voronkov M, Braithwaite SP, Stock JB, Mouradian MM. Protein Phosphatase 2A and Its Methylation Modulating Enzymes LCMT-1 and PME-1 Are Dysregulated in Tauopathies of Progressive Supranuclear Palsy and Alzheimer Disease. J Neuropathol Exp Neurol 2018; 77:139-148. [PMID: 29281045 PMCID: PMC6251692 DOI: 10.1093/jnen/nlx110] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Hyperphosphorylated tau aggregates are characteristic of tauopathies including progressive supranuclear palsy (PSP) and Alzheimer disease (AD), but factors contributing to pathologic tau phosphorylation are not well understood. Here, we studied the regulation of the major tau phosphatase, the heterotrimeric AB55αC protein phosphatase 2 A (PP2A), in PSP and AD. The assembly and activity of this PP2A isoform are regulated by reversible carboxyl methylation of its catalytic C subunit, while the B subunit confers substrate specificity. We sought to address whether the decreases in PP2A methylation and its methylating enzyme, leucine carboxyl methyltransferase (LCMT-1), which are reported in AD, relate to tau pathology or to concomitant amyloid pathology by comparing them in the relatively pure tauopathy PSP. Immunohistochemical analysis of frontal cortices showed that methyl-PP2A is reduced while demethyl-PP2A is increased, with no changes in total PP2A or B55α subunit, resulting in a reduction in the methyl/demethyl PP2A ratio of 63% in PSP and 75% in AD compared to controls. Similarly, Western blot analyses showed a decrease of methyl-PP2A and an increase of demethyl-PP2A with a concomitant reduction in the methyl/demethyl PP2A ratio in both PSP (74%) and AD (76%) brains. This was associated with a decrease in LCMT-1 and an increase in the demethylating enzyme, protein phosphatase methylesterase (PME-1), in both diseases. These findings suggest that PP2A dysregulation in tauopathies may contribute to the accumulation of hyperphosphorylated tau and to neurodegeneration.
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Affiliation(s)
- Hye-Jin Park
- Center for Neurodegenerative and Neuroimmunologic Diseases, Department of Neurology, Rutgers—Robert Wood Johnson Medical School, Piscataway, New Jersey
| | - Kang-Woo Lee
- Center for Neurodegenerative and Neuroimmunologic Diseases, Department of Neurology, Rutgers—Robert Wood Johnson Medical School, Piscataway, New Jersey
| | - Stephanie Oh
- Center for Neurodegenerative and Neuroimmunologic Diseases, Department of Neurology, Rutgers—Robert Wood Johnson Medical School, Piscataway, New Jersey
| | - Run Yan
- Center for Neurodegenerative and Neuroimmunologic Diseases, Department of Neurology, Rutgers—Robert Wood Johnson Medical School, Piscataway, New Jersey
| | - Jie Zhang
- Center for Neurodegenerative and Neuroimmunologic Diseases, Department of Neurology, Rutgers—Robert Wood Johnson Medical School, Piscataway, New Jersey
| | | | | | | | | | - Jeffry B Stock
- Signum Biosciences, Princeton, New Jersey
- Department of Molecular Biology, Princeton University, Princeton, New Jersey
| | - M Maral Mouradian
- Center for Neurodegenerative and Neuroimmunologic Diseases, Department of Neurology, Rutgers—Robert Wood Johnson Medical School, Piscataway, New Jersey
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Lee HY, Itahana Y, Schuechner S, Fukuda M, Je HS, Ogris E, Virshup DM, Itahana K. Ca2+-dependent demethylation of phosphatase PP2Ac promotes glucose deprivation–induced cell death independently of inhibiting glycolysis. Sci Signal 2018; 11:11/512/eaam7893. [DOI: 10.1126/scisignal.aam7893] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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41
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Therapeutic targeting of PP2A. Int J Biochem Cell Biol 2017; 96:182-193. [PMID: 29107183 DOI: 10.1016/j.biocel.2017.10.008] [Citation(s) in RCA: 117] [Impact Index Per Article: 16.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2017] [Revised: 10/13/2017] [Accepted: 10/16/2017] [Indexed: 12/19/2022]
Abstract
Protein phosphatase 2A (PP2A) is a major serine/threonine phosphatase that regulates many cellular processes. Given the central role of PP2A in regulating diverse biological functions and its dysregulation in many diseases, including cancer, PP2A directed therapeutics have become of great interest. The main approaches leveraged thus far can be categorized as follows: 1) inhibiting endogenous inhibitors of PP2A, 2) targeted disruption of post translational modifications on PP2A subunits, or 3) direct targeting of PP2A. Additional insight into the structural, molecular, and biological framework driving the efficacy of these therapeutic strategies will provide a foundation for the refinement and development of novel and clinically tractable PP2A targeted therapies.
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42
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Regulation of protein phosphatase 2A (PP2A) tumor suppressor function by PME-1. Biochem Soc Trans 2016; 44:1683-1693. [DOI: 10.1042/bst20160161] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2016] [Revised: 08/06/2016] [Accepted: 09/09/2016] [Indexed: 02/06/2023]
Abstract
Protein phosphatase 2A (PP2A) plays a major role in maintaining cellular signaling homeostasis by dephosphorylation of a variety of signaling proteins and acts as a tumor suppressor. Protein phosphatase methylesterase-1 (PME-1) negatively regulates PP2A activity by highly complex mechanisms that are reviewed here. Importantly, recent studies have shown that PME-1 promotes oncogenic MAPK/ERK and AKT pathway activities in various cancer types. In human glioma, high PME-1 expression correlates with tumor progression and kinase inhibitor resistance. We discuss the emerging cancer-associated function of PME-1 and its potential clinical relevance.
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Park H, Lee K, Park ES, Oh S, Yan R, Zhang J, Beach TG, Adler CH, Voronkov M, Braithwaite SP, Stock JB, Mouradian MM. Dysregulation of protein phosphatase 2A in parkinson disease and dementia with lewy bodies. Ann Clin Transl Neurol 2016; 3:769-780. [PMID: 27752512 PMCID: PMC5048387 DOI: 10.1002/acn3.337] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2016] [Accepted: 07/08/2016] [Indexed: 01/29/2023] Open
Abstract
OBJECTIVE Protein phosphatase 2A (PP2A) is a heterotrimeric holoenzyme composed of a catalytic C subunit, a structural A subunit, and one of several regulatory B subunits that confer substrate specificity. The assembly and activity of PP2A are regulated by reversible methylation of the C subunit. α-Synuclein, which aggregates in Parkinson disease (PD) and dementia with Lewy bodies (DLB), is phosphorylated at Ser129, and PP2A containing a B55α subunit is a major phospho-Ser129 phosphatase. The objective of this study was to investigate PP2A in α-synucleinopathies. METHODS We compared the state of PP2A methylation, as well as the expression of its methylating enzyme, leucine carboxyl methyltransferase (LCMT-1), and demethylating enzyme, protein phosphatase methylesterase (PME-1), in postmortem brains from PD and DLB cases as well as age-matched Controls. Immunohistochemical studies and quantitative image analysis were employed. RESULTS LCMT-1 was significantly reduced in the substantia nigra (SN) and frontal cortex in both PD and DLB. PME-1, on the other hand, was elevated in the PD SN. In concert with these changes, the ratio of methylated PP2A to demethylated PP2A was markedly decreased in PD and DLB brains in both SN and frontal cortex. No changes in total PP2A or total B55α subunit were detected. INTERPRETATION These findings support the hypothesis that PP2A dysregulation in α-synucleinopathies may contribute to the accumulation of hyperphosphorylated α-synuclein and to the disease process, raising the possibility that pharmacological means to enhance PP2A phosphatase activity may be a useful disease-modifying therapeutic approach.
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Affiliation(s)
- Hye‐Jin Park
- Center for Neurodegenerative and Neuroimmunologic DiseasesDepartment of NeurologyRutgers – Robert Wood Johnson Medical SchoolPiscatawayNew Jersey08854
| | - Kang‐Woo Lee
- Center for Neurodegenerative and Neuroimmunologic DiseasesDepartment of NeurologyRutgers – Robert Wood Johnson Medical SchoolPiscatawayNew Jersey08854
- Present address: Department of Biological SciencesKorea Advanced Institute of Science and Technology (KAIST)Daejeon305‐701Republic of Korea
| | - Eun S. Park
- Center for Neurodegenerative and Neuroimmunologic DiseasesDepartment of NeurologyRutgers – Robert Wood Johnson Medical SchoolPiscatawayNew Jersey08854
- Present address: Albert Einstein College of MedicineBronxNew Jersey10461
| | - Stephanie Oh
- Center for Neurodegenerative and Neuroimmunologic DiseasesDepartment of NeurologyRutgers – Robert Wood Johnson Medical SchoolPiscatawayNew Jersey08854
| | - Run Yan
- Center for Neurodegenerative and Neuroimmunologic DiseasesDepartment of NeurologyRutgers – Robert Wood Johnson Medical SchoolPiscatawayNew Jersey08854
| | - Jie Zhang
- Center for Neurodegenerative and Neuroimmunologic DiseasesDepartment of NeurologyRutgers – Robert Wood Johnson Medical SchoolPiscatawayNew Jersey08854
| | | | | | | | - Steven P. Braithwaite
- Signum Biosciences133 Wall StreetPrincetonNew Jersey08540
- Present address: Alkahest75 Shoreway Drive, Suite DSan CarlosCalifornia94070
| | - Jeffry B. Stock
- Signum Biosciences133 Wall StreetPrincetonNew Jersey08540
- Department of Molecular BiologyPrinceton UniversityPrincetonNew Jersey08544
| | - M. Maral Mouradian
- Center for Neurodegenerative and Neuroimmunologic DiseasesDepartment of NeurologyRutgers – Robert Wood Johnson Medical SchoolPiscatawayNew Jersey08854
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Kaur A, Denisova OV, Qiao X, Jumppanen M, Peuhu E, Ahmed SU, Raheem O, Haapasalo H, Eriksson J, Chalmers AJ, Laakkonen P, Westermarck J. PP2A Inhibitor PME-1 Drives Kinase Inhibitor Resistance in Glioma Cells. Cancer Res 2016; 76:7001-7011. [DOI: 10.1158/0008-5472.can-16-1134] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2016] [Revised: 08/16/2016] [Accepted: 09/08/2016] [Indexed: 11/16/2022]
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Hwang J, Lee JA, Pallas DC. Leucine Carboxyl Methyltransferase 1 (LCMT-1) Methylates Protein Phosphatase 4 (PP4) and Protein Phosphatase 6 (PP6) and Differentially Regulates the Stable Formation of Different PP4 Holoenzymes. J Biol Chem 2016; 291:21008-21019. [PMID: 27507813 DOI: 10.1074/jbc.m116.739920] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2016] [Indexed: 11/06/2022] Open
Abstract
The protein phosphatase 2A (PP2A) subfamily of phosphatases, PP2A, PP4, and PP6, are multifunctional serine/threonine protein phosphatases involved in many cellular processes. Carboxyl methylation of the PP2A catalytic subunit (PP2Ac) C-terminal leucine is regulated by the opposing activities of leucine carboxyl methyltransferase 1 (LCMT-1) and protein phosphatase methylesterase 1 (PME-1) and regulates PP2A holoenzyme formation. The site of methylation on PP2Ac is conserved in the catalytic subunits of PP4 and PP6, and PP4 is also methylated on that site, but the identities of the methyltransferase enzyme for PP4 are not known. Whether PP6 is methylated is also not known. Here we use antibodies specific for the unmethylated phosphatases to show that PP6 is carboxyl-methylated and that LCMT-1 is the major methyltransferase for PP2A, PP4, and PP6 in mouse embryonic fibroblasts (MEFs). Analysis of PP2A and PP4 complexes by blue native polyacrylamide gel electrophoresis (BN-PAGE) indicates that PP4 holoenzyme complexes, like those of PP2A, are differentially regulated by LCMT-1, with the PP4 regulatory subunit 1 (PP4R1)-containing PP4 complex being the most dramatically affected by the LCMT-1 loss. MEFs derived from LCMT-1 knock-out mouse embryos have reduced levels of PP2A B regulatory subunit and PP4R1 relative to control MEFs, indicating that LCMT-1 is important for maintaining normal levels of these subunits. Finally, LCMT-1 homozygous knock-out MEFs exhibited hyperphosphorylation of HDAC3, a reported target of the methylation-dependent PP4R1-PP4c complex. Collectively, our data suggest that LCMT-1 coordinately regulates the carboxyl methylation of PP2A-related phosphatases and, consequently, their holoenzyme assembly and function.
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Affiliation(s)
- Juyeon Hwang
- From the Department of Biochemistry, Winship Cancer Center, and the Biochemistry, Cell, and Developmental Graduate Program, Emory University School of Medicine, Atlanta, Georgia 30322
| | - Jocelyn A Lee
- From the Department of Biochemistry, Winship Cancer Center, and the Biochemistry, Cell, and Developmental Graduate Program, Emory University School of Medicine, Atlanta, Georgia 30322
| | - David C Pallas
- From the Department of Biochemistry, Winship Cancer Center, and the Biochemistry, Cell, and Developmental Graduate Program, Emory University School of Medicine, Atlanta, Georgia 30322
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Beier A, Teichert I, Krisp C, Wolters DA, Kück U. Catalytic Subunit 1 of Protein Phosphatase 2A Is a Subunit of the STRIPAK Complex and Governs Fungal Sexual Development. mBio 2016; 7:e00870-16. [PMID: 27329756 PMCID: PMC4916389 DOI: 10.1128/mbio.00870-16] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2016] [Accepted: 05/19/2016] [Indexed: 12/21/2022] Open
Abstract
UNLABELLED The generation of complex three-dimensional structures is a key developmental step for most eukaryotic organisms. The details of the molecular machinery controlling this step remain to be determined. An excellent model system to study this general process is the generation of three-dimensional fruiting bodies in filamentous fungi like Sordaria macrospora Fruiting body development is controlled by subunits of the highly conserved striatin-interacting phosphatase and kinase (STRIPAK) complex, which has been described in organisms ranging from yeasts to humans. The highly conserved heterotrimeric protein phosphatase PP2A is a subunit of STRIPAK. Here, catalytic subunit 1 of PP2A was functionally characterized. The Δpp2Ac1 strain is sterile, unable to undergo hyphal fusion, and devoid of ascogonial septation. Further, PP2Ac1, together with STRIPAK subunit PRO22, governs vegetative and stress-related growth. We revealed in vitro catalytic activity of wild-type PP2Ac1, and our in vivo analysis showed that inactive PP2Ac1 blocks the complementation of the sterile deletion strain. Tandem affinity purification, followed by mass spectrometry and yeast two-hybrid analysis, verified that PP2Ac1 is a subunit of STRIPAK. Further, these data indicate links between the STRIPAK complex and other developmental signaling pathways, implying the presence of a large interconnected signaling network that controls eukaryotic developmental processes. The insights gained in our study can be transferred to higher eukaryotes and will be important for understanding eukaryotic cellular development in general. IMPORTANCE The striatin-interacting phosphatase and kinase (STRIPAK) complex is highly conserved from yeasts to humans and is an important regulator of numerous eukaryotic developmental processes, such as cellular signaling and cell development. Although functional insights into the STRIPAK complex are accumulating, the detailed molecular mechanisms of single subunits are only partially understood. The first fungal STRIPAK was described in Sordaria macrospora, which is a well-established model organism used to study the formation of fungal fruiting bodies, three-dimensional organ-like structures. We analyzed STRIPAK subunit PP2Ac1, catalytic subunit 1 of protein phosphatase PP2A, to study the importance of the catalytic activity of this protein during sexual development. The results of our yeast two-hybrid analysis and tandem affinity purification, followed by mass spectrometry, indicate that PP2Ac1 activity connects STRIPAK with other signaling pathways and thus forms a large interconnected signaling network.
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Affiliation(s)
- Anna Beier
- Lehrstuhl für Allgemeine und Molekulare Botanik, Ruhr-Universität, Bochum, Germany
| | - Ines Teichert
- Lehrstuhl für Allgemeine und Molekulare Botanik, Ruhr-Universität, Bochum, Germany
| | - Christoph Krisp
- Lehrstuhl für Analytische Chemie, Ruhr-Universität, Bochum, Germany
| | - Dirk A Wolters
- Lehrstuhl für Analytische Chemie, Ruhr-Universität, Bochum, Germany
| | - Ulrich Kück
- Lehrstuhl für Allgemeine und Molekulare Botanik, Ruhr-Universität, Bochum, Germany
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Xia X, Gholkar A, Senese S, Torres JZ. A LCMT1-PME-1 methylation equilibrium controls mitotic spindle size. Cell Cycle 2016; 14:1938-47. [PMID: 25839665 PMCID: PMC4614068 DOI: 10.1080/15384101.2015.1026487] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
Abstract
Leucine carboxyl methyltransferase-1 (LCMT1) and protein phosphatase methylesterase-1 (PME-1) are essential enzymes that regulate the methylation of the protein phosphatase 2A catalytic subunit (PP2AC). LCMT1 and PME-1 have been linked to the regulation of cell growth and proliferation, but the underlying mechanisms have remained elusive. We show here an important role for an LCMT1-PME-1 methylation equilibrium in controlling mitotic spindle size. Depletion of LCMT1 or overexpression of PME-1 led to long spindles. In contrast, depletion of PME-1, pharmacological inhibition of PME-1 or overexpression of LCMT1 led to short spindles. Furthermore, perturbation of the LCMT1-PME-1 methylation equilibrium led to mitotic arrest, spindle assembly checkpoint activation, defective cell divisions, induction of apoptosis and reduced cell viability. Thus, we propose that the LCMT1-PME-1 methylation equilibrium is critical for regulating mitotic spindle size and thereby proper cell division.
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Affiliation(s)
- Xiaoyu Xia
- a Department of Chemistry and Biochemistry; University of California ; Los Angeles , CA , USA
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Pusey M, Bail S, Xu Y, Buiakova O, Nestor M, Yang JJ, Rice LM. Inhibition of protein methylesterase 1 decreased cancerous phenotypes in endometrial adenocarcinoma cell lines and xenograft tumor models. Tumour Biol 2016; 37:11835-11842. [PMID: 27048286 DOI: 10.1007/s13277-016-5036-8] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2015] [Accepted: 03/28/2016] [Indexed: 12/15/2022] Open
Abstract
Protein methylesterase 1 (PME-1) promotes cancerous phenotypes through the demethylation and inactivation of protein phosphatase 2A. We previously demonstrated that PME-1 overexpression promotes Akt, ERK, and may promote Wnt signaling and increases tumor burden in a xenograft model of endometrial cancer. Here, we show that covalent PME-1 inhibitors decrease cell proliferation and invasive growth in vitro but have no effect in vivo at the concentrations tested; however, depletion of PME-1 with shRNA in an endometrial cancer xenograft model significantly reduced tumor growth. Thus, discovery of more potent PME-1 inhibitors may be beneficial for the treatment of endometrial cancer.
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Affiliation(s)
- Michelle Pusey
- Oncoveda, Cancer Signaling and Cell Cycle Team, Medical Diagnostic Laboratories, LLC, 1000 Waterview Drive, Room 345, Hamilton, NJ, 08691, USA
| | - Sophie Bail
- Oncoveda, Cancer Signaling and Cell Cycle Team, Medical Diagnostic Laboratories, LLC, 1000 Waterview Drive, Room 345, Hamilton, NJ, 08691, USA
| | - Yan Xu
- Invivotek, LLC, 16 Black Forest Road, Hamilton, NJ, 08691, USA
| | - Olesia Buiakova
- Invivotek, LLC, 16 Black Forest Road, Hamilton, NJ, 08691, USA
| | - Mariya Nestor
- Pathology Department, Members of Genesis Biotechnology Group, LLC, Medical Diagnostic Laboratories LLC, 2439 Kuser Road, Hamilton, NJ, 08690, USA
| | - Jing-Jing Yang
- Pathology Department, Members of Genesis Biotechnology Group, LLC, Medical Diagnostic Laboratories LLC, 2439 Kuser Road, Hamilton, NJ, 08690, USA
| | - Lyndi M Rice
- Oncoveda, Cancer Signaling and Cell Cycle Team, Medical Diagnostic Laboratories, LLC, 1000 Waterview Drive, Room 345, Hamilton, NJ, 08691, USA.
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PP2A methylation controls sensitivity and resistance to β-amyloid-induced cognitive and electrophysiological impairments. Proc Natl Acad Sci U S A 2016; 113:3347-52. [PMID: 26951658 DOI: 10.1073/pnas.1521018113] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Elevated levels of the β-amyloid peptide (Aβ) are thought to contribute to cognitive and behavioral impairments observed in Alzheimer's disease (AD). Protein phosphatase 2A (PP2A) participates in multiple molecular pathways implicated in AD, and its expression and activity are reduced in postmortem brains of AD patients. PP2A is regulated by protein methylation, and impaired PP2A methylation is thought to contribute to increased AD risk in hyperhomocysteinemic individuals. To examine further the link between PP2A and AD, we generated transgenic mice that overexpress the PP2A methylesterase, protein phosphatase methylesterase-1 (PME-1), or the PP2A methyltransferase, leucine carboxyl methyltransferase-1 (LCMT-1), and examined the sensitivity of these animals to behavioral and electrophysiological impairments caused by exogenous Aβ exposure. We found that PME-1 overexpression enhanced these impairments, whereas LCMT-1 overexpression protected against Aβ-induced impairments. Neither transgene affected Aβ production or the electrophysiological response to low concentrations of Aβ, suggesting that these manipulations selectively affect the pathological response to elevated Aβ levels. Together these data identify a molecular mechanism linking PP2A to the development of AD-related cognitive impairments that might be therapeutically exploited to target selectively the pathological effects caused by elevated Aβ levels in AD patients.
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Sangodkar J, Farrington C, McClinch K, Galsky MD, Kastrinsky DB, Narla G. All roads lead to PP2A: exploiting the therapeutic potential of this phosphatase. FEBS J 2016; 283:1004-24. [PMID: 26507691 PMCID: PMC4803620 DOI: 10.1111/febs.13573] [Citation(s) in RCA: 230] [Impact Index Per Article: 28.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2015] [Revised: 09/29/2015] [Accepted: 10/21/2015] [Indexed: 12/22/2022]
Abstract
Protein phosphatase 2A (PP2A) is a serine/threonine phosphatase involved in the regulation of many cellular processes. A confirmed tumor suppressor protein, PP2A is genetically altered or functionally inactivated in many cancers highlighting a need for its therapeutic reactivation. In this review we discuss recent literature on PP2A: the elucidation of its structure and the functions of its subunits, and the identification of molecular lesions and post-translational modifications leading to its dysregulation in cancer. A final section will discuss the proteins and small molecules that modulate PP2A and how these might be used to target dysregulated forms of PP2A to treat cancers and other diseases.
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Affiliation(s)
- Jaya Sangodkar
- Department of Genetics and Genomic Sciences, Icahn School of Medicine at Mt. Sinai, New York, NY, USA
| | - Caroline Farrington
- Department of Medicine and Institute for Transformative Molecular Medicine, Case Western Reserve University, Cleveland, OH, USA
| | - Kimberly McClinch
- Department of Hematology and Medical Oncology, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - Matthew D. Galsky
- Department of Hematology and Medical Oncology, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - David B. Kastrinsky
- Department of Structural and Chemical Biology, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - Goutham Narla
- Department of Medicine and Institute for Transformative Molecular Medicine, Case Western Reserve University, Cleveland, OH, USA
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